These error messages will be displayed when creating Sales transactions (Sales Order, Invoice, Cash Sale) wherein the available quantity is less than the Reorder/Build Point.
To remove the warnings:
1. Navigate to Home > Set Preferences > Transactions tab.
2. Go to Warnings section.
3. Unmark the checkbox for Inventory Level Warnings.
4. Hit Save.
As per field level help, check this box to see warnings when you sell inventory items with quantities at or below their reorder points.
You must also set these minimum quantities at Lists > Items, on the Basic tab, in the Reorder Point field.
Please note that we do not have a general setting for this preference. Each user needs to change the individual setting.