Hi he yu ,
You can create a custom page by copying the 'TaskInbox' page of Workflow commons and modifying it, or you can change this page itself as you wish (although this is not recommended).
For the solution of the problem, use the Data grid, the list where you show your Tasks on this page. Activate multiple selections from the properties.
Add an action button to the Buttons section and design it as a call microflow. In this microflow, convert the status of the incoming tasks as parameters to reject. I hope it helps.