change of position

Ask your manager. They don't have to grant your request if there are no part-time positions available.

do they require a reason for this? i just want to take it slowly for now.

We cannot predict what your manager/employer will request/require. What answers you give will be up to you.

At my facility, you have to wait for a part-time job posting to become available and then apply for it (possibly competing with other staff). The department has a certain number of full-time, part-time, and call-in positions. Rearranging the configuration of those positions requires an act of congress here (which may not be the case everywhere). OP, if you think about it, it wouldn't make sense for your employer to just allow staff to go from full-time to part-time whenever they choose - they would have to create multiple new positions to cover the open hours. What happens when you decide to go from 3 shifts a week to 2 shifts a week? Who covers your 3rd now open shift? You may need to consider applying for part-time openings in other departments or with other employers.

I simply asked my manager and she said yes !!! I hope I don't have to ever go back to FT again. I love my 2 12s. Now if I had to I would .....

Review your policy for changing shifts, but always put it in writing.