How to Create Hard Drive Partition and How to Combine Multiple Partitions into a Single Partition.

It’s possible to create partitions and resize them without installing any extra software in Windows.
Naturally, there are partitions that are default to your PC and as such should not be touched such as all partitions before and including your C drive, others can be deleted.
Shrink Volume function is used to decrease a partition’s size.
Extend Volume is used to increase a partition’s size if there is an unallocated space adjacent space to the right.
There exist no Merge Volume functionality in Disk Management; partition merging is achieved indirectly only by using shrinking one volume to make space to extend an adjacent one.

If you're not exactly sure about a feature, do not attempt to make any changes to it.

If you're an average user and you don't demand much from your PC you probably won't miss having your PC partitioned.