Good day Francisco < @Francisco Leong >
(1) You should have more information in the notification. You can try again and when you get the error then click on it to get the full information. Usually it will say that there is dependency in another object (unfortunately is does not always say which)
I decided to delete the virtual machine and cancel the subscription.
(2) If you cancel the subscription then you probably do not need to clean anything. You can always open a free billing support ticket in this case and ask the support to remove since you cancel the subscription - this is related to billing issue if you cancel the sub
(3) If you want to remove everything anyway, then instead of removing service after service which might result which this issue if your do not remove the services in the right order (since there are dependencies in other services), then simply remove the entire resource groups
Removing the resource group with all the content should work (assuming all the related services created in the same RG)