I am trying to assess whether I should take on a skylight replacement job on screened-in porch roof which has a slight pitch. As I understand all I have to do is remove the shingles around the existing skylight, pry or unscrew the fasteners, remove any caulk or tar that seals out water, and then pull out the sky light.
I would then reverse the process by making sure the sealant is continous and full while I fasten the new skylight, then re-shingle so that water rolls off like it does on a ducks tail.
What type s/l exists and what do you intend to replace it with?
The "trouble bubble" type units rely on some type of sealant to keep them from leaking. A true curbed s/l (Velux FS, for instance) will typically have a flashing kit available with good instructions attached. Finding a replacement unit to fit the existing hole is sometimes a challenge.