Removing silicone caulk
 

How can silicone be removed from around an rv window so it can be properly
sealed with butyl. Complete removal is necessary so other material can
seal.

On my house, I use razor blades w/ razor blade holder/handle. Score a line
around the window gasket,then lay a razor blade flat and just peel it up.
There may be chemicals to do this, but they are likely strong, and may
damage the window seal, or damage the glass.

A heat gun on the low setting should help out quite a bit.