Dear Amin,
You can rename a road from edit option. Please do the following:
1. go Edit on the top
2. Select Road Segment
3. select the segment or segments you want to rename.
4. select Next
5. Edit road Names
6. under Edit road names you need to select remove from all option ( to remove the previous Name)
7. Add new name: .........type road name and select the type ( the new Name you want to add)
8. save...........
that's it