A colleague reaching the end of his career
I have a teacher in my school who is about to go into retirement. He’s not doing his work as expected. I have communicated his attitudes towards work to my superiors but to no avail. He is older than me and I find myself in difficulty in handling him. I need your help in how I can get him to work as expected. I count on your usual cooperation.

Perhaps he is worried about the future. Think about directing him to sources of support which can help him prepare for the impending financial and personal changes he faces.
But for the sake of your students you must encourage your colleague to give as much as he always has, if not more.
How you manage him will largely depend on both of your personalities, your relationship and existing procedures
It is your job to manage employees and their performance, and I assume you already have processes in place. Good people management is the best way to handle this issue. Continue to give feedback, set targets, motivate and develop all your staff, regardless of age and approaching retirement.
Talk to him about your expectations of his performance, and allow him opportunities to communicate openly.
Appeal to his professional pride in his record. Remind him that he wants his last couple of years to be a tribute to his career, with students performing well, and his exam results worthy of comment for their success.
If this doesn’t work you will need to manage him closely. Discuss goals and performance with him regularly. Use discussions to manage his under-performance.
Perhaps also consider a change in working patterns, or even reduce his responsibilities with less classes or shorter hours. Maybe you can use his expertise in a slightly different role, perhaps mentoring younger colleagues. This may help him perform more effectively.