How To: Remove unnecessary fields from the geodatabase after they have been imported from a coverage
ArcGIS does not permit the deletion of standard coverage fields after importing the data set into a geodatabase feature class. These fields can be removed from the feature class attribute table by turning the visibility off and exporting the new feature class.
Add the geodatabase feature class to ArcMap.
Right-click the layer in the Table Of Contents.
Click the Fields tab.
Click a field that you want to remove and uncheck the Visible check box.
Repeat step 3-5 for all desired fields.
Warning: Don't delete the OBJECTID, SHAPE, and SHAPE_Length fields from the Geodatabase. Deleting these fields may compromise the integrity of the geodatabase.
Right-click the layer name and select Open Attribute Table.
Make sure all the fields you want in the new attribute table are visible. If not, return to step 1. If they are visible, close the attribute table.
Right-click the layer name in the Table Of Contents and select Data > Export Data.
Set the Export dropdown list to All Features within the Export Data dialog box.
Click the Browse button and navigate to the geodatabase to store the new feature class.
Name the output feature class and click OK. You may delete the old feature class.