core/src/main/java/com/orientechnologies/orient/core/sql/OCommandExecutorSQLDropIndex.java
public Object execute(final Map<Object, Object> iArgs) {
    if (name == null)
      throw new OCommandExecutionException("Cannot execute the command because it has not been parsed yet");

    if (name.equals("*")) {
      long totalIndexed = 0;
      for (OIndex<?> idx : getDatabase().getMetadata().getIndexManager().getIndexes()) {
        getDatabase().getMetadata().getIndexManager().dropIndex(idx.getName());
        totalIndexed++;
      }

      return totalIndexed;

    } else
      getDatabase().getMetadata().getIndexManager().dropIndex(name);

    return 1;
  }
public Object execute(final Map<Object, Object> iArgs) {
    if (name == null)
      throw new OCommandExecutionException("Cannot execute the command because it has not been parsed yet");

    if (name.equals("*")) {
      long totalIndexed = 0;
      for (OIndex<?> idx : getDatabase().getMetadata().getIndexManager().getIndexes()) {
        getDatabase().getMetadata().getIndexManager().dropIndex(idx.getName());
        totalIndexed++;
      }

      return totalIndexed;

    } else
      getDatabase().getMetadata().getIndexManager().dropIndex(name);

    return 1;
  }
Execute the REMOVE INDEX.