How do i delete unwanted worlds

[Z3n0]

So i have for some reason lost a accidentaly got another world (SpeakerSMP_nether SpeakerSMP_the_end and SpeakerSMP) I do not want these worlds because I have "world" which is my main world on the smp so I installed MV (Multiverse) to try to delete the unwanted worlds    but it said "You can't delete this world" anyone got any ideas on how to delete them! Only plugins i have are EssentialsX and Multiverse but i can install plugins if that helps the problem.

[chillins]

Hey, in order to delete a world input the command format I have below.

Type in-game: "/del world (world)"