There’s no way to do that without dropping and recreating the table.
If you rt-click the table from the schema browser and choose “rebuild table”, Toad will give you a way to rebuild the table and then re-insert the data. This is NOT a good choice if someone might be using the table while you are rebuilding it.
For more of an online rebuild (and if I remember correctly, this method requires the DBA Module), go to the main menu -> Optimize, -> DBMS Redefinition Wizard. If you google DBMS_REDEFINITION you can get the specifics on how this works.