after taking out the peel and stick tile, there is still adhesive on the floor. can i just cover it with a 6 mil vapor barrier?

Hello Allan - thank you for your inquiry. Yes - basically two options with this scenario. Remove or cover. In your case, covering will work. Please ensure every area is covered. Another option would be to secure a 1/4" underlayment grade plywood on top of that area as well. Thank You -