In that Resource Monitor screenshot we can't see what is utilizing the disk so much at the moment, as that seems to be stuck at indexing.
with HTOP (so just type 'sudo HTOP' in your SSH console), this is possible...
I would then here sort the processes on IO_Read_RATE and probably from there you can find the process that needs to be killed (can also be done within this HTOP application).
Maybe that would help...?