Pull the bolts out that are on the forks midway on the forkplate, that will release the lowers (if they are not frozen to bad) I would try and carefully work the lower and upper edges of the boots with a very thin tool while oiling between them and steel (try no to pull or tear them if they are good) and get them loose before pulling the lowers totally off. If you can save them do it as what they are based off of the repops are a bit large and dont fit as well.
Only pics I had when I took my last Barris apart to rebuild but may help on the forks
can see in this pic the slotted holes that the bolts ride in, there is a spring inside the lower tube that rests against the bolt when assembled.
I cant remember if these were the repopped boots (they are for a certain BSA motorcycle if I remember correctly) or if I soaked and saved the originals but when I put them back on the bike upon assembly I did use some electrical tape to build up the tubing a bit to keep them from moving/sliding out of place on the tubing under the boot top and bottoms.