Re-use previous admin on reinstall

Hello,
Sorry as this must be a noob question.
How can we re-use a previously made admin account for a new install?
Had to reinstall seafile (on a windows 7 machine), though when the previous admin username and pw were entered when adding an admin account, an error message stated this was not possible.

Is it possible to force a new seafile install to use an already created admin account (with all data available in seafile when logged in online)?

Thanks