How do I reject a women without being a dick?

One of my friends has recently broke up with his ex girlfriend.

I was in the pub eailer tonight and both myself and her started having casual conversation. Nothing more, nothing less.

We made each other laugh a few times, as that's basic social skills. At no point would I of considered it flirting.

Once home, I received a message from her that said "Hey xx", along with a friend request on Snapchat.

I'm fully aware this sounds childish, but I guess that's how some people do it?

1. I'm not being a rebound hookup for a friend's recent ex.

2. She's a walking red flag, and no offence to her, but she's not an attractive women, 100% not worth the potential trouble.

As of right now, I've ignored all of it in hopes she'll move on to the next guy.

Should I just leave it alone and hope it works itself out?