I dont have any programming background, I see there is some python library to handle that but I just need a web site to do that is there any ?
I've just written an answer on quaro for same question which is,
There is an app for that, we’ve built a service to get backups while deleting Slack Messages at onces, it deletes 100 messages for free and 2500 messages for just $1,
We will add Skype, Facebook, Instagram services in future, but for now we only have available deleting services for Slack,
You can select, any channel, any person or you can set for all types of messages in Slack to delete.