Have Christians abolished sacrifices?

The author of Hebrews was eager to show the ineffectiveness of the Jewish sacrificial rites. He has successfully proved that the blood of bulls, the fats of rams could never take away sins although they had been offered continually (Hebrews 10:4). Christians possess a far superior sacrifice of the Son of God, who once and for all, takes away the sins of the world. John the Baptist bore this witness, calling Jesus the "Lamb of God" twice (John 1:29, 36).
The author of Hebrews focuses on Jesus' single sacrifice and his ascension instead. The author relies on Jesus' ascension to show the superiority of Christian sacrifice. The earthly priests offered sacrifices daily and yearly and failed to take away the sins of the people, thus bringing them closer to the sanctuary. Christ did it once and entered the heavenly sanctuary. We Christians hold on our faith in Jesus and obtain admittance.
But when Christ had offered for all time a single sacrifice for sins, he sat down at the right hand of God,
then to wait until his enemies should be made a stool for his feet (Hebrews 10:12-13, Psalm 110:1b).
The author of Hebrews did not elaborate on the image of "a stool for his feet" which is probably an echo of the image of bruising the serpent's head (Genesis 3:15). Rather, he focuses on the effectiveness of Jesus' sacrifice which cleans all our sins, elevate us to a sanctified life.
For by a single offering he has perfected for all time those who are sanctified (Hebrews 10:14).
The author was confident of his conclusion because he found in Jeremiah 31, a prooftext to show that in this New Covenant established by Christ, God would ignore our sins.
then he adds, "I will remember their sins and their misdeeds no more." (Hebrews 10:17, Jeremiah 31:34b)

Through his Passion/Resurrection, Jesus has established this New Covenant in which God will ignore our sins. It was enough for Jesus to die once to save the world. Christians find it absurd for Jesus to die repeatedly, like those bulls and lambs offered in the Temple. The effect of his sacrifice is eternal. Therefore, Jesus needs not die repeatedly.
Now what about the other functions of offering sacrifice, say thanksgiving and communion? Should Christians offer sacrifice to thank God or simply do away with sacrifice and do something else instead? How do Christians show their solidarity and communion in ways other than sacrifices? Obviously, offering sacrifice is only one of the many ways to express thanksgiving and communion. Liturgical theologians will offer us enough suggestions to get things done. Let's turn to other issues.
King David had lamented his plights as follow.
For I know my transgressions, and my sin is ever before me (Psalm 51:3).
Here is an example to show the ineffectiveness of the previous sacrifices. Yet it serves a function healthy for our spiritual life. It reminds us of our need of God's mercy. The superiority of Christian sacrifice championed by the author of Hebrews suffers a hidden weakness. The New Covenant, in which God ignores our sins, gives Christians a freedom never before enjoyed by anybody, not even King David. It is a new license to commit more sins. Given a new freedom, who would not exercise it, and exercise it to the maximum?
Theologically, God ignores our sins. That doesn't mean we are immune from the consequences of sins. We are not yet bulletproof and even if we are bulletproof, we will inflict harm on others. St. Paul understood this loophole well. He devoted another epistle to discuss freedom and warned against abusing it. Here is a quotation.
For you were called to freedom, brethren; only do not use your freedom as an opportunity for the flesh, but through love be servants of one another (Galatians 5:13).
Good advice. St. Paul skilfully imposes a limit on freedom with charity.

Dear Lord, without Your love, we are nothing. With love, we can be edifying. Make us Your instrument of justice and peace. Amen.

Appendix:
then to wait until his enemies should be made a stool for his feet.
τὸ λοιπὸν ἐκδεχόμενος ἕως τεθῶσιν οἱ ἐχθροὶ αὐτοῦ ὑποπόδιον τῶν ποδῶν αὐτοῦ (Hebrews 10:13)
ἕως ἂν θῶ τοὺς ἐχθρούς σου ὑποπόδιον τῶν ποδῶν σου. (Psalm 109:1b LXX, 110:1b).

"This is the covenant that I will make with them after those days, says the Lord: I will put my laws on their hearts, and write them on their minds," then he adds, "I will remember their sins and their misdeeds no more."
αὕτη ἡ διαθήκη ἣν διαθήσομαι πρὸς αὐτοὺς μετὰ τὰς ἡμέρας ἐκείνας, λέγει κύριος· διδοὺς νόμους μου ἐπὶ καρδίας αὐτῶν καὶ ἐπὶ τὴν διάνοιαν αὐτῶν ἐπιγράψω αὐτούς,
καὶ τῶν ἁμαρτιῶν αὐτῶν καὶ τῶν ἀνομιῶν αὐτῶν οὐ μὴ μνησθήσομαι ἔτι. (Hebrews 10:16-17)
ὅτι αὕτη ἡ διαθήκη, ἣν διαθήσομαι τῷ οἴκῳ Ισραηλ μετὰ τὰς ἡμέρας ἐκείνας, φησὶν κύριος Διδοὺς δώσω νόμους μου εἰς τὴν διάνοιαν αὐτῶν καὶ ἐπὶ καρδίας αὐτῶν γράψω αὐτούς,
καὶ οὐ μὴ διδάξωσιν ἕκαστος τὸν πολίτην αὐτοῦ καὶ ἕκαστος τὸν ἀδελφὸν αὐτοῦ λέγων Γνῶθι τὸν κύριον, ὅτι πάντες εἰδήσουσίν με ἀπὸ μικροῦ αὐτῶν καὶ ἕως μεγάλου αὐτῶν, ὅτι ἵλεως ἔσομαι ταῖς ἀδικίαις αὐτῶν καὶ τῶν ἁμαρτιῶν αὐτῶν οὐ μὴ μνησθῶ ἔτι. (Jeremiah 38:33-34 LXX, 31:33-34 MT)