Overwrite Discord Messages?

I want to sell my laptop soon and want to make sure that all data is irretrievably deleted. I would like to test the whole thing on Discord first and would therefore like to delete the group chat messages first.

My first question is: which program is particularly suitable for overwriting or irretrievably deleting data (in this case from Discord).

The second question is, in which folder do I have to go in to delete the data, if this is necessary.

Third question: should I do this several times?

If you can still see inconsistencies in my execution, I would be happy if you would point them out to me.

The messages etc. From Discord are stored in your account

Just uninstall Discord and it's all gone.

You can also format your hard drive, then everything will be erased, you should generally do this before selling off your device

Yes, but if I wanted to delete them, then the data would still be stored somewhere, only the storage space is marked as 'free', right?

Your Discord messages are stored on Discord servers, but e.g. Your login information or user token will be stored locally. So you can only delete chat messages yourself using Discord's "delete function" and these are then irrevocably deleted & can no longer be viewed by Discord.

I can only advise you to format your hard drive either completely or not at all - otherwise important data will be gone afterwards that you will miss later and you will not achieve the desired success with Discord either - everything is on servers. For the complete formatting of an entire hard disk there are instructions from https://www.pc-magazin.de/ratgeber/festplatte-restlos-loeschen-sicher-saeubern-ssd-secure-erase-anleitung-hdd-3196204.html, with which all data is gone.

Yes, but if I wanted to delete them, then the data would still be stored somewhere

No, they wouldn't.

The Discord messages are not saved on your PC.