You can use Multipart To Singlepart tool from Data Management tools\Features\Multipart To Singlepart
to creates a feature class containing singlepart features generated by separating multipart input features
or
You can use Explode on the Advanced Editing toolbar to separate a selected multipart feature into its individual, component features. This would be useful if you needed to alter the attributes of one of the elements in a multipart feature.
- Click the Edit tool on the Editor toolbar.
- Select the multipart feature you want to separate into individual features.
- Click Explode on the Advanced Editing toolbar.
The parts of the multipart feature become independent features, with each one being assigned identical attribute values.
Regard,
Kelvin.