Edit enum combo box

Dear…

How can I edit a combo box containing Enum values?? i.e. inside the payment journal lines form in AR we have the account type, I want to show only bank and customer types for the user ??

I tried to add the following code inside the enter method (for the comboBox)

this.delete(enum2str(LedgerJournalACType::Ledger));

this.delete(enum2str(LedgerJournalACType::Vend));

this.delete(enum2str(LedgerJournalACType::FixedAssets));

this.delete(enum2str(LedgerJournalACType::Project));

However, this wont work properly…the account lookup will have some problem once I try such thing.

Any clue ??

Any help ??