Some managers may find it challenging to deal with an employee who is not performing to the required standard, so as manager, the first step should perhaps be a focus on changing how the employee is dealt with. It is crucial to set clear standards around communication; ensure the employee knows what is required of them, take time to go through the job description, their role and if part of a team what is required at all levels. This should include job requirements, job standards and expected outcomes at both individual and team level, if that is a requirement.
Giving clear constructive feedback, be precise, don’t ramble, and be very clear about what you expect as an outcome and give timeframes. Be supportive and if you can provide support [can be through you as Manager or perhaps other team members]. Put a performance management plan in place and set clear timeframes and regular check-ins during that time-frame. Document and record and get employee [and/or the team] to 'sign off'. This ensures both the individual employee and/or team are clear about what is required at all levels. It also sets the scene clearly that if improvements are not made where the non-performance may revert then to a more formal process through the workplace policies and procedures.