Re: 'Delegation'
Ah well, in that case, the 'In Emergency, Break Glass' box is your friend. As you were then an ex-employee, you were technically being 'detained unlawfully against your will', and entitled to use 'reasonable force'* to escape said 'unlawful detention'. In addition, as an unescorted visitor, any injuries you sustained in escaping the 'unlawful detention' would be the responsibility of your ex-employer and therefore litigable.
:o)
I cannot help feeling there is a sub-'Diehard' action thriller that starts with the recently fired employee (hero) being unable to leave the building and therefore the sole inhabitant over the weekend the 'bad guys' decide to enact their felonious little plans ...
*Unreasonable force involves things like smashing the whole place down or setting off the sprinklers, one has to have some sense of proportion, after all.