Originally Posted by
WhyFi
It'll be more trouble to half-ass it, so whole-ass it and do the job right - remove the tape.
Pull it off. You might need to clean up some sealant residue, but a damp paper towel should do.
This, exactly this. Then get a clean rag and some isopropyl alcohol, and get the rim good and cleaned up before putting the new tape on...I cannot reiterate how important this is. A clean rim is much less trouble to work with when setting up a tubeless tire. A little extra work at the outset will give you months of trouble free use.