A friend of my Mothers has some shops, which she rents out.
One of her tenants consistently keeps the shop closed, and does not pay his rent for months on end, this time he has not been seen for 6 months. He has not got a lease on shop, just a verbal agreement , and has stock left in the shop, and the keys of said premises.
The lenght of time is very important, but if it is just 2 or less than three years and there is no written agreement then if he pays monthly give one months notice in writing, if weekly, give one weeks notice. The notice should state that at the expiration of the time the keys should be surrendered and the stock removed and if not, the locks will be changed and the stock stored and the tenant is to be liable for the costs, and if stock not collected within a reasonable time it will be disposed of. It would be worthwhile to get some legal advice specific to the situation where your mother's friend can give full information to a legal adviser and get specific feedback.