It is not possible to convert a bank account to normal account (or vice-versa) per se.
However, we understand why you may want to do this - so there are some workarounds depending on your situation...
If there are no entries or balances to date in the existing account then:
The simplest solution is: delete the existing account and recreate with the same details (Code / Account Name / Class) in the new format you require (i.e. add again as either a 'bank account' type or 'normal account' type)
Do this via the Chart of Accounts:
If there are entries or balances to date in the existing account then:
It won't be possible to delete the existing account (as above).
So, instead we suggest you do the best alternative action as follows:
If you really want to keep the same code for your new account, then firstly change the code on the existing account to a new 'redundant' code (i.e. you won't want to use again)
Then add the new account you want (either a 'bank account' type or 'normal account' type)
Next, reduce the old account balance to NIL by adding a single 'bank statement batch' entry line (either a payment or receipt amount) to the normal account to clear it
Therefore if there was a balance in the account to start, everything is switched and you now have the account in the format you require for future entries.
In the next period (after you close and roll forward this period, via 'Period end routine') you should be able to deactivate the old account.
It would not be possible to deactivate it in the current period if you performed the entry to remove any remaining balance. See below:
