I want to make a easily removable cover to protect strawberry plants .

Frost cover or old flat sheets.

Put 4 sticks or posts around the outside and drape a sheet over the sticks at night.

Protect from what?

If you have an old tomato cage place it in the pot and cover with a sheet or painters plastic, tucking the corners under the pot to prevent the wind from blowing it off. The tomato cage will allow the strawberry runners a place to grow and support the fruit as it develops.

I have strawberry plants in my raised garden. At the end of season last year, I cut the plants down to soil level, leaving root systems intact. Then I put cardboard over them and a few big rocks in corners. They will remain like this until after last frost of the year has passed. Then uncover and water and mulch. I hope this helps you. The home grown strawberries are so worth it.