Executor does not want to sign

[Maximiliano Rodriguez]

Zac and Bern's sister died, her name is Mary. Mary leaves the house to Bern as heir to the house as stated in her will. Bern wants to sell the house. Zac is the executor of the will and he doesn't want to sign (he hides and does not to talk to anyone to do his job as executor). The house is foreclosure in two weeks.

Bern want to sell the house, what are his options?