You must not ignore objectionable behavior of difficult people. People who are disruptive, antagonistic, condescending or just generally hard to get along with are not going to change, or leave without supervisory intervention.

• As with any employee action begin with the development of documentation outlining the nature of the difficult behavior, the impact on the workgroup, and required changes.
• It may be helpful to confirm your views of the person discretely and confidentially with other supervisors who may have experienced or observed the troubling behaviors.  Dealing with a difficult or disruptive personality is a little different than dealing with unacceptable behavior in general. The difference may lie in the inherent nature or personality of the person. They may not realize what effect or reaction they are having on others within their work group. The objectionable behavior may not be intentional.  It may just be how the person receives and reacts to new information.
• Take time to try to understand the employee, including matters they be dealing with in their personal lives.  The act of showing empathy may be one of the most important steps in dealing with difficult people. Having this information may prepare you for the frank conversation you must have with them.
• Invite the employee in for a conversation about the issues. Be direct and specific about the behaviors that are impacting others in the work group.  Consider opening by asking then if  it would surprise them that  they are viewed by members of the workgroup  as someone who  is difficult to work with?  It is not uncommon to find out that they are indeed surprised by this. From this point on,  you have a basis upon which you build your conversation.  If possible, involve the employee in helping to identify what changes in behaviors must occur if they are to remain a member of the work group.
• Establish a clear timeline during which behavior will be monitored and when, if the behaviors are not modified, further corrective action will be taken. Do not sugarcoat the possible consequences of not making the needed change. Make sure they understand that their continued employment is at stake.
• Continue your documentation with details of the conversation, specific modifications that are required, timelines established for required improvement, and any subsequent progress made or additional corrective action taken..
• Do not let the issue go unresolved. Follow up!