My storage usage is over the Basic limit and I can't access my files to delete them.

CTFT wrote:

I didn't want to sync all my files to dropbox and now I'm over my limit and can't access any files so I can go below this limit.

Being over your limit doesn't block access to your files. If you're using the Dropbox folder on your computer all of your files are still accessible and you can move files out of the folder that you no longer want in your account. Restarting the Dropbox application after that should reindex your files and syncing should resume if you're back below your limit.

Additionally you should be able to access your files through the Dropbox website and delete files to go back below your limit. Just make sure you've moved those files out of your local Dropbox folder as well or they could be deleted when syncing resumes.

CTFT wrote:

Syncing has been stopped but what happens to my files on my computer if I cancel my dropbox account - will they get deleted ?

No, your files will not be deleted if you close your Dropbox account. The best way to accomplish this would be to exit and uninstall the Dropbox application on your computer first, and then delete your account. Uninstalling first, while not necessary, ensures there's no longer a connection to Dropbox.

CTFT wrote:

I've since changed computers and transferred files / folders to the new desktop. Does dropbox have a link to my computer?

If you didn't install the Dropbox application on the new computer, then there's no connection between it and Dropbox.