How to delete Others?

The question then is:
If you don't know what "Other" is, and you don't know where "Other" is, how do you know it is not something you need to keep?
You will discover if you search around on your storage drive that no files or documents are identified as "Other" but are simply called what they are.
"Other", for Storage purposes, is simply everything that is not included in the other categories (Apps, Audio, Photos, Movies, and Backups). It's just a general designation that the system uses, but isn't necessarily tied to anything.
"Other" can be your system files, your documents and other data files, and several other possibilities.

--- Post Merged, May 20, 2016 ---

The problem is that storage chart is notoriously inaccurate. You could get a better picture of what you have by rebuilding your Spotlight database. That will then likely show you a more accurate chart, but the chart will simply go off again after some time.

Better - would be to use one of the techniques in the various threads here that cover "how do I find out what is using the space on my Mac", or something similar. That will help you decide which large files you have, and you can decide if you need to keep them. And, you can come back here if you have some question about what to keep (and what to remove )

 

Yes, and that is the point. "Other" is, well, other!
The best thing to know is what "Other" is not: Audio, Photos, Movies, Backups, and Applications.
Everything else is "Other" (There are lots of files that fall under "Other", and that depends on how you use your system. The problem that you have is - you can't search for "Other", as it is just a general designation by your system for various types of miscellaneous files, but the files are not stored that way. It is simply applied by the Spotlight database. That's why you want to try rebuilding your Spotlight database.

If you want to clean up your storage, the theory that you want to follow is to drill down through your hard drive, find the items that take up a lot of space, then decide if you need them. If not, delete them.
Takes a while, but that's basically how you do it.
Search here for threads that go into more detail how to proceed in cleaning up your hard drive. You will find literally dozens.