Forgive me but I'm pretty green when it comes to these F5's. We have an F5 LTM that is load balancing our internal and external email. We just had a pen test done and they saw TLS1 and 1.1 open from ...
HI, Not sure it makes much difference but is this HTTPS or SMTP traffic? (only interested for possible context later) now, what you want to look at is your client ssl profile.
Inside there is selection's for "no tls" or "no tls1.1" etc etc. So by selecting the ones you don't want it will turn them off.
The way i did it, was to use a cypher profile, and link that to your ssl profile. This meant i could have granual control not just of the encyrption used (TLS) but also the hashes which also came up on a pen test for me! Have a look if that answers your question, if not let me know and i can send you some links or screen shots.