Deleting the bass clef

In the layout tab

1. Open the Layout or Instrument (depending on which version you have) panel (yellow highlight below).

2. Find the instrument in question: in my example, it's a harpsichord. Click the triangle to the left (yellow highlight below) to expand the staves in the instrument.

3. Click the staff you want to remove to select it. (yellow highlight below) At upper right, you'll see a 'trash can' icon (green highlight below). Click there to delete the staff. If there is a chance you might want to keep it around for future use, you can simply hide the staff, by 'closing the eye' at left (blue highlight below)

In the event you choose to delete it now, you can recreate it in future if necessary by returning to this place, clicking on the instrument, and clicking the button to Add staff (below the staves).