What are you intending for the property? Ceilings are easily replaced. Beyond that your question is more like “ how long is a piece of string.” Are you doing the work ( this is a diy site ).
Walls should be plastered after install ideally but as they were already plastered window fitters should have used a trim ( if they were replacing existing they would have used a trim ).
Builders are being petty because you didn’t go through them .
Black trim is a quick and easy fix, you could...
It’s all in the linked post .
Basics here.
It’s twin walled so ripped the rear every panel to reduce it to single thickness which bends easily.
Lay ply or board over top edge to mark shape of curve , cut this out and fix to floor inline to hold the base of panel and finish with pvc trim to form...
Slab out side door looks high , also does appear to be cement infill back to wall which suggests it was installed with a space which would have prevented rain running back to air against wall , exterior matt also keeps area wet .
No problem to remove as it’s 6 individual panels , so you can remove just one or all.
I left spares under the bath just in case but need to access is very rare .