Presume they are Microsoft Windows memory dump files. If so, it should be ok to remove them. You might also want to check what is in the Recylce bin before emptying.
If Disk Clean up says they are ok to remove then remove them.
Microsoft are hardly going to offer to remove important files with Disk Clean up are they.
You may also want to choose the "Clean Up System Files" option. You are then offered "More Options" and if you select that you can clear out "System Restore and Shadow Copy" files.
This is all in Window 7 so you may not have the same options on your Windows.