At this point you might want to sand, seal and glass the deck. While the resin is still 'green', or uncured, it will be flexible.

If you can then remove the deck you'll have much easier access to the hull and forms. If the deck is stuck too you'll just free it when you free the hull.

The forms get removed through the cockpit. If you are planning on hatches you could cut those openings now and give yourself a bit better access.

Stick a 2x4 through the cockpit or hatch and position one end on the nearest form near the seam line between deck and hull, and, about 1/2 inch inside of the hull strips. Line up the 2x4 so it is as close as you can get to being inline with the length of the boat, and tap the free end sharply with a hammer. Move the end of the 2x4 an inch or two down on the form and tap it again. Repeat this process, working your way around the edge of the form until you have loosened the form.

If you have an internal strongback you'll want to cut out as big a piece as possible to give you more room to work and to let the forms twist a bit as they break free.

Once the 3 center forms are free you can flex the hull and deck a little, which makes it a little easier to remove the remaining ones.

Really tough spots can be weakened by using a heat gun inside the boat. Aim it at the edge of the forms and keep it moving. Heat an area then tap it to get it free. Don't worry about this hurting the glass you've applied. The strips are great insulators. The inside will get hot enough to melt or soften glue and epoxy but the outside won't even get warm.

You may need to use a large screw or hook eye screwed into the form as a handle so you have something to pull on to get the frame out.

A lot of tapping and those forms will come free.
PGJ