How can I delete a client from my TP link app if there is no option to delete in settings. All my other clients have the --- to select to delete but this one device does not have that option in settin

Upgraded to 1.5.1 via the app and my network is crippled! Prior to this firmware I had amazing throughput on my devices and internet speed tests at 100% my ISP rated service (200MB). Now I get .12MB,