By default, IGMsg sends a short "Automation powered by @igmsg_com" message after your DM. On a paid plan you can switch this off so your DMs are fully unbranded.
Upgrade to a paid plan
Removing branding is a paid-plan capability. Open Billing from the sidebar and upgrade to a plan that includes "remove branding" (Pro and above).
Open your branding settings
Go to Settings → Profile and find the Branding section.
Turn off the branding footer
Toggle Hide "Powered by IGMsg" footer on and save. New DMs will no longer include the footer message.