Things that we, as a fan base, can do:
1. Do not buy the kit or anything with the sponsors logo on
2. Protest against the club's decision in a noticeable manner (i.e. banners, singing anti-sponsor songs)
None of the companies (PTT, LCFC, nor King Power) will want the spotlight shone on them in this way. It may not make a difference now, but hopefully it will be something considered in future sponsorship deals.