How can I add space to my partition?

A couple of days ago, I had deleted a useless partition on my computer and created 45.6GB of unallocated space there. Yesterday, my computer gave a low disk space notice and asked me to extend my C partition. So, I just planed to add the unallocated space to my C partition. But, I don’t know what I should do in details. So, I came here. How can I add the unallocated space to my C partition step by step? Help me, please!

1). Back up everything important well.
2). Open Disk Management: Right Click “My Computer” to open “Manage” > find and click Disk Management in the left side
3). Right click your C partition to highlight “extend”.
Or you also can directly use a partition resizing tools to help yourself out in several clicks, like GParted, IM-Magic Partition Resizer Free and Paragon Partition Master, etc.
Note: Never forget to make data backups in case of data loss.

Two solutions:
1). Directly extend it in Disk Management.
2). Extend it with the help of professional expanding programs.
Here is a video tutorial that will teach you to extend your partition step by step:
https://www.youtube.com/watch?v=6jCeT7CbsKk
I hope it will give you some clues. Of course, before resizing process, always remember to back up everything important well.