A Tower Controller in Charge reported the Local Controller gave instructions to an arriving aircraft which resulted in conflict with opposite direction traffic. When the arriving aircraft landed the same controller issued taxi instructions to the aircraft which caused a conflict with another taxiing aircraft.

Narrative

The local controller is a terrible controller. An airplane came in with minimum fuel wanting to land. Controller talked the airplane in to trying to land XXR on a 2 mile final at 4000 feet. Obviously didn't work. As the in charge I told him it wouldn't work and downwind him for XYL which was the original plan from approach. Controller did not do that or issue any other control instructions and aircraft departs off XXR straight into arrivals for XY. Aircraft then cuts left in front of another aircraft on 2 mile base for XYR. That aircraft I don't believe was ever even cleared to land XYR. After all that the local controller tried to taxi the PA-28 into the ramp via Taxiway 1; Taxiway 2; to cross XYL. There was a PC-12 on [Taxiway] 2 he forgot about that he was working. He talked the PA-28 into almost smashing into the back of the PC-12. Myself and another controller had to tell him to stop taxiing the PA-28 because of the PC-12 on taxiway 2. The PA-28 had to slam on his brakes because they came to within 10 ft of each other. Suggestion: Recommend pulling this controllers certifications and to retrain. Controller has safety issues happen daily because of capacity and ability and lack there of without management holding him accountable or taking it seriously.