Most of the time when I go on the asset store, DL something, and close it, it comes back later.
It won’t leave me alone!
KEEEEL ITT!!
But seriously, why does this keeping happening.
It won’t leave me alone!
Click “Close” at the bottom right?
You mean the button to close the picture?
Hmm. Def something wrong. Didn’t have this problem happen to me before. Perhaps ur unity is still trying to access the assets store.
Have the same problem too. Restart Unity… that helps 
Try using the pull-down menu from the upper right of the asset store, and selecting “log out”. Hope that helps.