Please use the below command to check all the azure bastion hosts.
az network bastion list
If any bastion hosts are present, you can delete them using below command :
az network bastion delete --name MyBastionHost --resource-group MyResourceGroup
After deleting your bastion host, make sure to delete your public IP created for bastion host.
Please use the below command to delete public IP :
az network public-ip delete -g MyResourceGroup -n MyIp
For more details please refer to the below document for the pricing of Bastion :