Is it okay to buzz cut my hair on day 10 after FUE?

It is best to ask your surgeon about post operative care as each doctor has their unique regimen.   There is nothing wrong with cutting your hair in general.

10 days should be fine to cut your hair. Some doctors say two weeks but at 10 days your grafts are pretty well established it'd take something pretty strong to really do damage to them.

We
tell our patients that after 10 days they can resume all activities including
strenuous activities.  A buzz cut should
be fine especially if all the scabs have healed and fallen off.  Do not razor shave at that time.

as long as all of the scabs are gone you are fine to do a buzz cut to your donor area. Typically by day 10 all of the scabs are gone as long as you followed your post op care carefully.

As long as the extraction sites are healed it is ok to buzz cut your hair by day 10. Your grafts should be fine at this point.

All of the grafts are sealed in place after 6 days and the donor area will tolerate a buzz cut after a week.  If you have sterile instruments, you could buzz cut it immediately.  As soon as the skin is healed over and there is no open oozing, buzz cutting is fine.  Oozing usually ceases by the second or third day after your procedure.  

Once all the scabs are off in the donor area you may resume buzzing it with clippers. Therefore at day 10 you should be fine to resume. 

AT 10 DAYS WITH ALL CRUSTS OFF, YOU CAN BUZZ CUT YOUR HAIR WITH NO PROBLEMS AS HEALING SHOULD BE COMPLETE

Yes, you should be fine to buzz cut your hair after 10 days. It is very important to take extra caution with your grafts for the first 7-10 days. After 10 days they should be fairly stable and you can begin to resume your regular activities. 

You should be okay as long as the crusts are gone and the skin is healed.  Studies of the healing show that about day 9 is when your grafts are set in place and by that time the little donor area sites should be healed as well. Good Luck!