How do I removing files in my storage?

For starters, see > Free up storage space on Mac - Apple Support

If you are looking to free up a large amount of space without paying extra to use iCloud..?

You can move and store your Photos, Music, Movie Libraries to an external hard drive.

Move your Photos library to save space on your Mac - Apple Support

Change where your music files are stored on Mac - Apple Support

Move your iMovie for Mac library - Apple Support

Click on View Storage Settings and follow the recommendations.

You can also move some files (like Photos) to an external disk then move back later if you have enough room.