Welcome to the Microsoft Q&A Platform. Thank you for reaching out & I hope you are doing well.
I understand that you have deleted a VNET Integrated service before removing the Integration, which resulted in the ServiceAssociationLink being abandoned and stuck in the VNET.
To troubleshoot further, we will need a specialized 1:1 session, where a support engineer can have a screen share session and manually delete the ServiceAssociationLink.
If you have a support plan you may file a support ticket, else please do let us know, we will try and help you get a one-time free technical support.
Cheers,
Kapil