Re: To reduce NTA storage size, removing Netflow Sources

1. From the NTA Summary page, click on the Manage Sources button (provided your SW account does have rights)
2. Expand the Cisco tree (which shows nodes sending flows in the last 15 minutes by default)
3. Click on each of the nodes and then unselect any interfaces for which you do not need NTA data
4. Click Submit when done

By the way, you can also force DB cleanup by launching the NetflowDatabaseMaintenance.exe file. That application file is located on your core server (Program Files\SolarWinds\Orion\NetFlowTrafficAnalysis folder.  Once you launch it, you should see something similar to the screenshot below.  By the way, you'll notice the Wizard recommends for the SW services to be stopped if you intend to do a Full Shrink.  The Full Shrink will hep you regain space on your DB, but will cause some downtime as you know.  If you do cannot afford to shut down SW for a while, just select the same options as per the screenshot below.  I hope this helps.Image may be NSFW.
Clik here to view.