Help removing old insulation from behind wall panels

[Girlwith9Lives]

Hi y’all,
I’m brand new so please forgive me for sounding amateur!
I’ve been trying to find a thread or YouTube to answer this but I think I just need to ask for help. I’m converting it mostly by myself so I have been learning one step at a time.
My bus is a Girardin on a Chevy Express 3500 chassis. I’ve gotten most of the interior stripped & it seems to be in great condition, but the wall panels by the floor have me stumped. The upper ones had rivets and they came off, but the lower ones seem to be bolted to the frame, and they include the chair rails. I saw the threads on here saying *don’t remove your chair rails!*
There’s old insulation behind these little pockets and it seems the only way to get it out would be to cut the panels open. They seem to be an important part of the structure and I don’t want to collapse my bus haha. Should I just leave it?
Thank you so much in advance, any and all advice is really really appreciated!

[nikitis]

Use the curly end of a crow bar, Stick it in at an angle as you insert it downwards into the insulation, most will come out, then repeat to get the rest.

Worked really well for me. It acts as a hook and will bring that stuff right up.

[peakbus]

I used multiple tools to reach in from the top and pull it out. Then I slid in rigid foam.