soak it in vinegar to remove the rust.
Or first create a solution of half ammonia and half vinegar. Dip the nickel plated steel object wholly into the solution for half an hour. Then, remove the object and wipe dry. Application of a chrome polish will help restore shine.
or:
1
. Scrub off the rust with a steel wool pad or a kitchen scrubbing pad. Surface rust comes off easily.
2
. Make a paste of two parts table salt and one part lime juice in a bowl. Apply the paste to the steel with a paper towel.
3
. Leave the paste on the rust for two to three hours "Non Toxic House Cleaning" an article suggested by Earth Easy in eartheasy.com.
4
. Dampen a paper towel and wipe away the paste and the rust. Dry the area with a paper towel.