I'm going to move PBIs(product backlog items) with its tasks to another teamwork board project, but I couldn't find an option to do this, it would be so helpful if anyone could help me.
In the Azure DevOps Server, you can change the work item type or move work items to another project within a project collection, these features require that the data warehouse is disabled.
Disable warehouse steps:
Open Azure DevOps Server Administration Console->Reporting->Click the button Disable Reporting->Enter the server name to confirm.
Then you can see the button move to team project and change type… in the Drop-down list.