unknown dropbox storage counted on my computer

I wonder if anyone can help with this vexing problem? I used to have & use dropbox (light version) for local file storage, but then ran out of the 2 gb of free space fairly quickly. I did at one stage take up a free offer to test out aditional data storage, and did load up many more items, but decided not to actually proceed with signing up for the extra facility. Initially, that resulted in me constantly getting alert messages saying I had exceeded my data storage limit, so I progressively deleted almost all of the extra material, to bring it down under my free limit again.

I then transferred everything to a connected external ssd drive, thus freeing up needed space on my laptop. The problem - which has occurred repeatedly - is that whenever I simply reconnect my external drive to the laptop again, it mysteriously automatically RELOADS  all of that data again into my laptop memory. More exactly, it automatically counts an additional 95GB of data against my laptop's memory. I have been stuggling with HOW to locate exactly where such data is then stored, and even after uninstalling dropbox (together with any visible associated files), my laptop stills displays the previous dropbox amount of data, on my C drive!

I really do need to get rid of this unwanted wasted memory space from my laptop, but cannot find how to achieve this!

Can anyone help?