1. you can cleanup your disk,delete the useless files to get more space.
2, you can use Registry Edior---HKEY_LOCAL_MACHINE---- Software--- Microsoft--- Windows ---CurrentVersion---Policies, if there is no Explorer, you need add the new file and named it; if there is, you do need to add one. Add the DWORD, named NoLowDiskSpaceChecks, insert 1 as the value. Reboot the computer.
3, you can extend partition. MiniTool PW free edition can help you. The Extend, Resize/Move, Merge, Split function are efficient and easy to operate.