High RAM usage with Minecraft is normally caused by either a map issue or a broken plugin.  To test this you'll need to temporarily run your server on a different map and see if that fixes the usage, if not then it'll be an addon issue.  In that case the easiest thing to do is to remove all the addons from your server then add them back in small groups to see when the high RAM usage starts again.
Please Note: RAM usage is a value taken over time so any changes will need to be left for a while to show improvement.

To temporarily run a new map on your server;

* Go to Clanforge -> Profiles -> Edit -> Configs

* Select your server.propeties file from the File: list

* Change the level-name=world line to level-name=world2  (this needs to be a world you haven't used before)

* Save the profile and restart the server

You can change back to your original world by resetting the level-name= line to what it was orginally.  Usually level-name=world

You can add and remove addons from Clanforge -> Profiles -> Addons.