Hi 

Sage drive shouldn't turn off by itself, it is possible you open a duplicate copy of the file?

If that is no the case, and you are the owner who uploaded it initially, you can you download it and save a local copy then unshare it. and then upload a proper updated version. 

If you cant download and cant find original shared copy, then you would have to upload it under a slightly different name

Currently Sage drive management centre does not have "delete" option yet.

hope this helps