Deleting Indexes 
Prerequisites
You are logged on to the database as a database user.
You are the table owner or have INDEX privilege for the table.
More information: SQL Reference Manual, Privilege Specification (privilege_specification)
The database is in the ONLINE operational state.
Procedure
In the context menu of the table to which the index belongs, choose Definition.
In the context menu of the editor window, choose Edit.
Open the Indexes tab page.
In the context menu of the index, choose Remove Index.
More Information
SQL Reference Manual, DROP INDEX Statement (drop_index_statement)