I just changed mine a few months ago. There is nothing very easy about it and it takes a lot of elbow grease.
I experimented with various tools and ended up using a $30 multifunction tool from harbor freight once the screws were removed. The vibrating tools gets the putty hot so you have to clean the tool every few minutes. The nice thing is that it did eliminate a lot of the elbow grease from the other methods that I tried.
Ours was punctured with hail. It was two thin pieces when it came out. I replaced it with a 1/4" thick unit using the larger outside dimensions. Since we are traveling now in the winter in 10 to 30 degree weather, there is a lot of condensation on the inside in the mornings, just like the side windows.
Right now, I need a clever way to seal from the vertical trim boards in the shower up to the skylight. Any Ideas anyone?
Larry Fritz