Not able to delete local zone group

I have enabled local zone in "India (Kolkata) - ap-south-1-ccu-1".

I'm trying to disable or delete the above local zone. I am not able to to disable it. I have removed all the resources from that local zones.

Below are the steps which I have followed :-

1. I went to EC2 zones section
2. Earlier I had enabled kolkata local zone. Which I now need to disable it

3. Gone to Local Zones and clicked on Manage ( India (Kolkata) - ap-south-1-ccu-1 )
4. Under the Zone group I have selected Disabled radio button

5. After that clicked on Update zone group
6. After that getting a pop up like below & I am unable to disable it:

Disable Zone Group To disable a Zone Group, you must contact AWS Support. To ensure that your request is completed as quickly as possible:

1. Remove all resources from the zones in the Zone Group.
2. Open an AWS Support case titled ‘Disable Zone Group’. After you disable a Zone Group, existing resources in its Zones continue to run and incur charges until you stop, terminate, or delete them.

Can anyone please help me to disable the local zone.