However, you could optionally save and unsave Snapchat messages that are temporarily important.
The following instructions apply to the iOS and Android Snapchat apps, though the screenshots are from an iPhone.
Android users should be able to follow along but might notice some small differences.

Pixabay
Why Save and Unsave Snapchat Messages?
bring up the individual orgroup chat boxwith your saved message (or messages) by tapping it.
All saved messages are highlighted in gray; identify the one that you want to unsave.

you could’t select multiple saved messages in bulk to unsave them.
After you successfully unsave a message, it is no longer highlighted in gray.
Likewise, when someone else in the chat saves a message, it saves for everyone.
Unfortunately, you’re free to’t remove a message on behalf of someone else.
Clearing conversations only removes them from your main conversations tab.
you gotta follow the instructions above to unsave your saved messages.