Block users from charging your tenant – How to disable self service purchases
Users can explore or purchase Microsoft 365 products on their own, without needing help from an administrator. However, to prevent unexpected costs, admins now have the option to turn off self-service settings for any product. This stops users from making purchases.
By default, self-service trials and purchases are enabled for all products, but admins can control whether users can make these purchases. If you want to stop users in your organization from trying or buying products on their own, you can easily manage this.
In the Microsoft 365 admin center, you can disable self-service settings for each product to avoid any unwanted charges.
-> Login to office 365 admin center – Settings – Org Settings – Self Service trials and purchases
Click and find all the available products on your list. From here you can disable the available products. By default the products are all available for try or buy.
Go ahead and disable this Feature :
Periodically you have to check for new products and disable them because by default will be enabled !