Navigate to the shared folder you want to permanently remove from your Dropbox account.
Click Share next to the folder.
Click the dropdown next to your name.
Click Remove my access.
If you remove your access to a folder accidentally, you will need to ask the owner of the shared folder to invite you again.
Owners: How to remove a member from a shared folder
If you need to make sure that someone no longer has access to a shared folder, you can either remove a member or unshare the folder.
When you remove a member a folder, that member loses access to the shared folder. When you unshare a shared folder, all members lose access to the shared folder. You can choose to leave members a copy of the folder, but it won’t sync with anyone else’s copy.
Owners, and sometimes editors, can remove members from a shared folder. Owners can choose if editors can manage access to a shared folder.
Remove a member from a shared folder using dropbox.com
Navigate to or search for the shared folder you're interested in.
Hover over the folder and click Share.
Click the settings icon (gear icon).
Click Unshare folder.
What happens when I unshare a folder?
When you unshare a folder:
The files are immediately removed from each member's account on dropbox.com.
The files are removed from each member's linked computers the next time the Dropbox desktop app syncs. However, the files are cached for a short time.
The files are permanently deleted from each member's account. Former members can't recover these files.
How to let someone keep a copy of a shared folder
When you unshare a folder or remove a member from a folder, you can choose if they can keep a copy of that folder:
If you choose to let the member keep a copy, they have a copy of the folder from the point in time when you remove them or unshare the folder. To avoid confusion, you can let them know that their copy will no longer sync with other accounts.