How to Delete preset?

There is no way to delete presets. 

...But...

There are two options:

1. Just modify the preset you don't love until you love it and so overwrite it:)
2.  Create a new tag named, lets say, "NOT IN USE" and overwrite this horrible boring disgusting preset attached to this tag. And now you just filter your presets selecting other tags and never ever ever select this "NOT IN USE" tag.