Removing rough-in plumbing in basement.

Hello,

I'm in the process of finishing my basement. One section has a rough in for a bathroom, however I have no need for an additional bathroom. There are 2 drain pipes sprouting from the concrete. I wanted to shorten these pipes so they are flush with the concrete. Is that possible? See pic. Maybe chisel away some concrete, cut a few inches off the pipe, cap it then use self leveling concrete around it?

Also there is plumbing running up the wall which just appears to be the vent or stack. Can I cut this? Unfortunately the guy who framed the place didnt frame the wall in front of the pipes (i think he was trying to save me space). The vent pipes as is are going to need a big budge to sit behind the drywall and im worried my sheet rock will crack.

Any thoughts are appreciated. Thanks.