so can lock or cannot lock ? 

Wanna ask...

If the tenancy agreement has expired long ago and the tenant chose not to renew or move out, is he or she considered trespassing?

Go to court, register at the counter for a case, then you need to hand over the papers to the tenant directly by hand. You can send by registered post, but sometimes they won't accept it, so it is quite troublesome. Best way is to hand over personally.

Similar situation here, tenant not paying rent.
After Google then only realized cut electricity / water is illegal one.

Dunno why property law is so protective to tenant but not owner.
The one who made the law think property owner must be so rich?
It is mostly middle income people who struggling to pay back the loan every month.

Really stupid law.