This part of GOV.UK is being rebuilt – find out what beta means

HMRC internal manual

Self Assessment Manual

Records: SA and permanent notes: deleting an SA note (Action Guide)

An SA Note generated automatically cannot be deleted.

Where you want to delete an SA Note, follow steps 1 - 2 below

1. Use function MAINTAIN SA NOTES to view the SA Notes already recorded
2. Select the line number of the SA Note you want to delete, then
  * Select the [Delete Note] button. You will be asked to confirm your action
  * Select the [OK] Button if you want to delete the SA Note. The automatic SA Note ‘Note made by 9999999 on dd/mm/yyyy deleted’ is created. (Note: 9999999 is the PID of the operator who made the SA Note that has now been deleted)