In Lansweeper, anything discovered on the network is treated as an asset, and assets are grouped into broad technical categories (servers, desktops, networking equipment, OT, users, software, etc.).
For IT devices, “Windows” is one of those core, system‑managed categories.
For assets that were discovered as Windows machines:
The Asset type = Windows is set automatically by the discovery logic.
That field is locked because Lansweeper uses it internally for:
Discovery/scanning behavior (which protocols/queries to run)
Normalization and reporting logic.
If you are linked to the cloud, it is possible to change it there however it is not possible to change it in the on-prem classic console.