Resource guarding

This is what I think this is called. Our two year old Westie is a loveable affectionate little dog until its time to get up off his bed in the morning or get off the sofa at night to go out for his wee. He will then bark, snarl and bare his teeth and will really go for me if I try to push him off.
Any suggestions on how to remedy this please. I did ask this question once before but sensible answers this time would be appreciated. Thank you.

teach him 'off' by luring him with yummy treats

1 Buy the Book Mine! A guide to resource guarding in dogs by Jean Donaldson, the best book on the subject and also available on Kindle I think.

2 Attach a short houseline to your dog (only whilst you are present) without a loop so that you can remove the dog from his spot without confrontation, do not look at dog, or negotiate, just call his name in a jolly hockey sticks approach, and toddle off, so he has not choice but to follow whilst you drop treats like Hansel and Gretel on the floor so he has a reason to get up.

If you feed him dry food, you could choose ONLY to feed him at these times and in this way, to change his view about staying in his place.

HTH

Teach him `come` with a treat, but start when he`s not comfortable. When it`s a learned response (he does it always) use it when he`s comfortable.
And stop pushing him out of bed?