Go to the Account section of your Settings and turn off the Gallery Sync in your Dropbox account. If it's not there, you can also go into the Gallery, hit the Menu button, go into Settings, and change your Dropbox Sync settings.
Thanks! That worked to remove them from my Gallery. BUT they still remain on the device in the Cloudagent/cache/dropbox folder. They use 92mb and I would like to SAFELY remove them.
Look at the settings under "Accounts" then "Backup Options" section then "Cloud". Should be a setting there under "Content Sync" for "Pictures" and for "Videos" to appear/not appear in Gallery/Video Player. Might help, it worked for me.