Please refer the steps below to delete the added product in purchase:
Step 1: Kindly go to the bills >> Click on Purchase and Select the bill >> Click on the three dots >> Click on edit
Step 2: Click on + Add more items (notice there are two products now)
Step 3: Delete the quantity >> Click on continue
Step 4: Earlier, there were two products. Now, you will notice that only one remains. Please click on Update
