One thing I would suggest - is going through them. Anything you know you will never use, delete.
I keep patterns in a folder by themselves and often I rename them when I save them. Sometimes they save with weird codes like dcs97812.cde.htm - Titles like that mean nothing, and by labeling with the real pattern name saves a lot of time.
When a pdf file is confusing or too large, I save the pattern info, maybe one pic instead of all of them, and other necessary info on another document like Word, then delete the pdf.
Another idea might be keeping a list of the files you do have - on a program like Microsoft Access - you could list pattern name, when completed, how much yarn you used, needle type/size. This would help in tracking your used patterns and make it easier to delete things you start realizing you really have no interest in making.
I have received patterns in email for cabled items. I can’t do cable, and because I have a unique visual disability, I doubt I’ll ever be able to cable or use dpns. So, deleting those makes sense, for if I do reach a point to try, I could find new patterns at that time instead.