Everything here is done from inside the ExcelDisc Chat app, by you, and takes effect immediately. There is no form to fill in, nobody to email first, and no waiting period. If you no longer have the app, there is an address at the bottom of this page.
Each of these is immediate and needs nobody’s approval. None of them deletes your account.
Write to info@exceldisc.com from the email address the account uses — that address is what identifies it, so a request from it is proof enough. Say whether you want the whole account deleted or only particular data, and it will be done and confirmed back to you. The same address handles any question about what is held.
You can also take a copy of everything before you go: ⋮ → Chat backup produces
an archive of every conversation your account can see, and ⋮ → Contacts
exports your contacts as a .vcf file any phone will import.