Hello Sunnideb,
It sounds like you have a shared folder and no longer want or need access. To modify settings for all shared folders, first log into your account at Dropbox.com, and click on "Shared" on the left side. This list returned will be all shared folders and files. If you want to remove a folder from displaying in your files (which count towards your available quota) or syning to your local hard drive (which take up space), click the "three dots" on the right side of the item in question, and select the item "Remove from Dropbox."
If it's an item you shared with someone, the option may appear as "Unshare," in which case you will need to also delete it to remove it from consuming resources.
Removing from Dropbox will still show the folder listed in the shared items; if you want to permanantly remove your access, by selecting the three dogs again and clicking "Remove" will ask for your confirmation to completely remove access, otherwise you can rejoin a shared folder at a later date, assuming you still are permitted access and have enough availble space.
Hope this helps,
-AB
