To resolve this error message you would need to delete any discount button that uses the discount or remove the discount from that button
  1. .Click Tickets > Configure daily sales page
  2. Click the arrow next to the discount that is tied to the button
  3. Click delete
  4. Repeat steps 2 & 3 for all discount buttons tied to the discount
You can also remove the discount from the discount button
  1. Click Tickets > Configure daily sales page
  2. Click the arrow next to the discount > click edit
  3. Change the discount in the name field
  4. Click save