How to empty a full memory

I am currently at a 91% memory use. I deleted some big files and still stayed at the same memory. Is there a trash bin I need to empty?
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Error: move package "requirements.txt" to requirements.txt

I usually install spacy with:
!pip install spacy

Today, when I ran my notebook, it said:

And I was not able to import spacy. I clicked on the 'move package "spacy" to requirements.txt' which created a requirements.txt file with spacy in it. But thn it gave me this:


And I still can't import spacy. I'm guessing it's a new feature because I never encountered this problem.

Can't import a big number of files

I'm trying to import 10k files where each file is around 5KB. I tried to import it all in the file section (it took about 10 hours). It said that all the files were imported, but when I closed the 'Upload files' window, only 2k files were imported. 

I tried to use the 'Shared dataset' like recommended, but when I try to import, it freezes the browser, even when I try to import only 1k files. Is there another way to import a big number of files?