Tap and hold on a Chat in Android and it selects. A tick appears beside it. You can continue to tap on other chats to select multiple chats. A Bin icon will appear at the top to delete them.

I don't see what's so difficult about that.

[and, like a previous commenter, I never delete chats either but I sussed that out in about 2 seconds by following the standard Android convention of tapping and holding on items in a list, to make multiple selections.]

I also find it odd you condemn Telegram for its 'poor interface' when it's generally recognised as being one of the most polished of the various chat apps you list.

I've recently come to Telegram after years of using Wire and becoming frustrated with its stagnated development and user-hostile dev team. Before settling on Telegram, I also kicked the tyres on Signal and several other secure messengers and Telegram was lightyears ahead of them all, in terms of features and usability.