Heb 10:10 By the which will we are sanctified through the offering of the body of Jesus Christ once for all.
Heb 10:11 And every priest standeth daily ministering and offering oftentimes the same sacrifices, which can never take away sins:
Heb 10:12 But this man, after he had offered one sacrifice for sins forever, sat down on the right hand of God;
This doesn't mean that the day is done away with, but under the new covenant, it's observance has been modified. If you still have trouble understanding, then I would suggest reading all of Hebrews.
Of course it does. Hebrews does not indicate the day was merely changed. It indicates the day was abolished with the passing away of the old covenant with the priesthood and sacrificial rituals.
"For I will be merciful to their unrighteousness, and their sins and their lawless deeds I will remember no more." In that He says, "A new covenant," He has made the first obsolete. Now what is becoming obsolete and growing old is ready to vanish away." (Heb. 8:12,13)
All of the pold covenant ritual days passed away. There is no other way to read the words written in Hebrews.