Drop Down Box Entry Removal

[angel_keen]

Is there a way to remove selections from a drop down box? ECC 6.0 will add manual entries to the drop-down box and they will stay until there have been enough entries after that to knock it off the list. If I enter a typo in a field where there should only ever be one entry, like the Z below, it will stay there indefinitely, and I have to click around it each time I want to choose the correct entry of Z1. It gets inconvenient pretty quickly when doing these changes en masse. Thanks for any tips!