If you are on the new gnome terminal that uses dconf, this is a bit more complicated, but still doable:
Profiles are stored with UUIDs, you need to find the UUID of the profile to delete:
dconf dump /org/gnome/terminal/ | less
Find the entry visible-name='...'that matches the profile you want to delete. See above for a section heading like [legacy/profiles:/:...]. So the full name of the item you want to remove is /org/gnome/terminal/legacy/profiles:/:.... Delete it this way:
dconf reset -f /org/gnome/terminal/legacy/profiles:/:...
Side note: this Q&A should probably be moved to unix.stackexchange.com.
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