To remove numbers from your Numberlab account start by login into the portal. Once you are logged into the portal you will select "Numbers" on the top navigation bar, from here you should see a list of all the numbers currently being managed on your account.
From here you will search for the particular number or numbers you wish to delete. If you are having trouble finding the number in the list try using the function "Ctrl + F" to search for the number on the list. Once you have identified the number(s) you will click the "delete" button in the numbers row to remove it from your account.
You should no longer see those numbers on in the "numbers" tab however do note you may still see those numbers on your main dashboard if they were run in a previous report. The next time a report is run you will no longer see those numbers on the dashboard.