Clients type version - let the only one

[Pa3k]

Hello there,

I would like to ask you guys If there is a possibility to configure server to show the only one version during the "sign in window" (see attachment).
How to remove/delete the other version ?
We are using zimbra version 8.7.1_GA_1670.FOSS.

The second question is If we can disable (to stop forcing) standard (html) client type version when for example the internet is slow.

If yes (for both questions) what should be the steps please ?

Many thanks!

Pa3k