Bottle weaning

Hey mumma's I'm a ftm and seeking a little help from other mummy's on here.

How can i wean my 15 month old off of his day time bottle?

He has 2 bottles a day one for his day time nap and the other when he goes to bed at night, i have started to reduce the amount he has from 260mls to 100-140mls but he drinks it then and plays around in his cot throwing his blanket and pillow out then continues to cry to try get me to go in there which i do when his cry is serious. Am i doing this right or should i just ditch the bottle all together for his day time nap?