Follow these steps:
1. Go to Infrastructure and click on the device with the full disk
2. Click on File Systems under Components
3. Select the disk on the right
4. Click the Gear then Monitoring, then choose No
5. Click the gear then Locking, check both boxes and hit submit

What kind of filesystem is it You can also choose to ignore it under Configuration Properties using Name: zFileSystemMapIgnoreNames

Good Luck!

Hydruid

Another option is to select the filesystem, then click on "Templates" under the Display: dropdown (just above where the graphs are shown), then click on the "Override Template" button (which will create a local copy of the monitoring template on the component), then double click on the threshold on the right and disable it. That will allow the filesystem to continue being graphed but not actually generate alerts. The better method is the one that Hydruid suggested above provided that you don't care about the utilization on the filesystem at all. I just wanted to explain the potential alternative to this so that you are aware.