how to respond to cob texts

I did formal recruitment in the fall and it didn’t work out. I keep getting text messages from some of the sororities inviting me to do COB and I’m not totally interested in joining those sororities. I don’t wanna be rude and just not respond but I don’t know how to tell them I’m not interested without sounding mean or hurting their feelings. Nothing against any of the sororities/these girls, I’m sure they’re all great, I’m just not interested in these specific sororities. Any advice on how to respond?