Delete local music

[Jim111]

hey community.

i just have a simple question: 

i have moved my local music from my notebook to an external harddrive.

now i have the problem, there are 2600 songs in my local musik inside spotify desktop app but i cannot play them because they are moved.

i want a clean new local music libary and want to delete all of them and get just the few i want inside and not all my music.

the problem is, i cant delete the songs inside there.

also a reinstall didn't help.

so how can i delete all songs in the local music libary in the win10 desktop app ? 

Best regards

Jim