Issue: your C drive shows insufficient space despite your efforts to reduce the amount of applications and data.
Resolution: Download Easeus Partition Master Free Edition, and merge the C partition with the Data partition. Save any data on the Data partition to a USB stick – you can restore it later.
Check you have the manufacturer’s recovery disks to hand, and that you are familiar with the procedure for using them before using EaseUS partition master. I have re-sized my partitions without having to execute a recovery procedure, but you never know.
After performing this operation, set the machine to perform a “Check disk” on reboot. (From the globe a the bottom left of the screen, go up to “Computer”. Right-click on the ‘C’ drive Windows partition, go down to Properties, choose the ‘tools’ menu click “Check Now…” ).
If you still want a DATA partition, use EaseUS partition master to re-create it.
If you still have insufficient space, the “Jetclean” program will remove redundant windows files and caches.