This spell is identical to a Ward spell except that it is cancelled by a Dispel. In all other respects, this spell follows all the rules for a Ward, including the use of Lesser Investment.
If you wish to upgrade your Wizard Lock into a Ward, you must first Dispel the Wizard Lock.
The building must be visibly marked with a large “W” to indicate the presence of a Ward or Wizard Lock.
There is no way to tell the difference between a Ward or a Wizard Lock just by looking at it; the only way to tell is to cast a Dispel at the portal and see if it remains. You must have a marshal present to do this.