As you know, SolarWinds doesn't have the function to unmanage several nodes at the same time without node administration rights. Therefore, I developed a UI interface based on Python and dash as python library.
You can add all the nodes you need and schedule them to be unmanaged.
API method:
Load Nodes Data: https://localhost:17774/SolarWinds/InformationService/v3/Json/Query?query=SELECT+NodeId,Caption,Ip_Address+FROM+Orion.Nodes
The UI is in Spanish.
The UI has a button to load nodes using SolarWinds API Rest

We need to load nodes to use other functions.
Then we already see all nodes:

Then we can create the schedule event, using SolarWinds API Rest method.
Unmanage Nodes: https://localhost:17774/SolarWinds/InformationService/v3/Json/Invoke/Orion.Nodes/Unmanage

At the end clic on "Programar Mantenimiento" bottom.

We receive a response message.

If we make a SWQL query to see this, we get:

I really appreciate your comments, please feel free to contact me in any case.