Sometimes when a customer gets set up on Dropbox they choose to sync everything to a user.
This may be a problem as their data grows, or if they just have a lot of data and their user's have a relatively small hard drive or little free space.

First check and see if Dropbox is seletively syncing files, or if it is just syncing everything.

Open the little dropbox icon in your taskbar by clicking the it.

This will bring up the Dropbox application where you will click the settings wheel.

This will bring a dropdown menu from where you will pick "Preferences".

This will bring up the DropBox Preferences window, where you will click on the "Account" tab.

This will bring up items relating to your specific account as seen below:
Click the "Selective Sync" button about half way down and to the right.

This will bring up the "Selective Sync" window as shown below.

From here you can drill down into directories just like you would on the File Explorer.
Everything may be checked and that might be why you are using up a lot of hard drive space.
I would suggest that you un-check everything, and the selective work you way down each tree and check only the folders that you want to have sync'd automatically to your computer.

NOTE: You will still have complete access to the folders and files that are not sync'd and can look at them and download them at anytime when you have internet access. If you selectively sync too many files, it could fill up your hard drive and compromise the operation of your computer, so choose wisely.

Once you are done, click the update button and Dropbox will start the selective sync for you.
This may take a while depending no how many files where being automatically sync'd to your computer.
If you were using up a lot of space on your hard drive, much of it may be free'd up for you once the selective sync'ing process is complete.

NOTE: You will see 2 little blue circular arrows indicating selective sync is in progress.
It will go away and be replaced by a green check mark when complete.