There indeed are plugins that can help with this, but it is a much better solution to get it right at the source. There are plenty of materials on the web that demonstrate proper recording techniques, use of pop filters, mic positioning and such.
Why not? I use mine all the time. You have installed the latest Tools for MR, right? Hint: read the MR816 manual. Hint 2: in Cubase, Devices/Audio Hardware Setup. Hint 3: Where have you assigned the onboard FX to be active?
Not intending to be cryptic about it, just to prompt you to use your available info and think it thru. Once you understand, you’ll be a better engineer.