Can a commerical landlord in the State of Washington lock you out, for non payment of lease at 30 days, without posting notice?

Whether for a commercial or residential rental, a landlord may not resort to self-help in removing a tenant from the premises. Locking out a tenant or turning off the utilities would be instances of self-help.

For a commercial rental, if the parties cannot agree with each other what their rights are, they can take each other to court. Their agreement may specify arbitration, mediation, or some other means of resolution.

You should review your specific facts with your attorney to see what legal options you have.