How can I delete Minecraft Forge?

Do you want to delete forge, or do you want to delete the profile? They're two different things; the profile allows you to launch forge, but deleteing the profile will ultimately leave Forge still on your disk.

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I just want to remove the profile.

Usually, to delete a profile, you just select the "..." menu and then hit delete.

Since that isn't there, you'll have to edit your launcher_profiles.json file, located in the .minecraft folder and remove the corresponding profile definition.
You might want to rename it to something else so that you can identify it.

I want to remove Forge (the install)

Do everything above first that uses the version* you want to delete, then go to your .minecraft folder and inside the /versions folder, look for your corresponding Forge's folder and delete it.

*Basically, if you want to remove anything forge, obviously remove all profiles that use a Forge version of Minecraft.

If there is nothing there, you're using an instanced copy of Minecraft (look in its own particular .minecraft folder instead), for example, if you are using the Twitch Client, which is %userprofile%TwitchMinecraftInstall by default.