How do i tell my maid of honor that i want my other friend to take over?

So, my current maid of honor has not been reliable or approachable or helpful but she's a really good friend of mine. She doesn't answer my phone calls and rarely responds to my texts until I express my disappointment my other friend who lives in another state has been really supportive and has been in contact with me constantly offering help and advice and always being there when I needed to talk to her and I really want her to be my maid of honor because she has been so supportive of me this entire time. How do I tell my current maid of honor that she's not supportive enough for me and I prefer another friend to take over?