Clear Row ⌃⌘⌫ – Logic Pro X keyboard command of the day

  Clear Row  ⌃⌘⌫

Clears the current row in the Step Sequencer. Only one row is the active focus at any one time.

Edit Step Sequencer rows in Logic Pro – Apple Support

To clear all row values: Choose Functions > Clear All Row Values from the Step Sequencer menu bar.