core/src/main/java/com/orientechnologies/orient/core/metadata/schema/OPropertyImpl.java
@Deprecated
  public OPropertyImpl dropIndexes() {
    getDatabase().checkSecurity(ORule.ResourceGeneric.SCHEMA, ORole.PERMISSION_DELETE);

    acquireSchemaReadLock();
    try {
      final OIndexManager indexManager = getDatabase().getMetadata().getIndexManager();

      final ArrayList<OIndex<?>> relatedIndexes = new ArrayList<OIndex<?>>();
      for (final OIndex<?> index : indexManager.getClassIndexes(owner.getName())) {
        final OIndexDefinition definition = index.getDefinition();

        if (OCollections.indexOf(definition.getFields(), globalRef.getName(), new OCaseInsentiveComparator()) > -1) {
          if (definition instanceof OPropertyIndexDefinition) {
            relatedIndexes.add(index);
          } else {
            throw new IllegalArgumentException(
                "This operation applicable only for property indexes. " + index.getName() + " is " + index.getDefinition());
          }
        }
      }

      for (final OIndex<?> index : relatedIndexes)
        getDatabase().getMetadata().getIndexManager().dropIndex(index.getName());

      return this;
    } finally {
      releaseSchemaReadLock();
    }
  }
@Deprecated
  public OPropertyImpl dropIndexes() {
    getDatabase().checkSecurity(ORule.ResourceGeneric.SCHEMA, ORole.PERMISSION_DELETE);

    acquireSchemaReadLock();
    try {
      final OIndexManager indexManager = getDatabase().getMetadata().getIndexManager();

      final ArrayList<OIndex<?>> relatedIndexes = new ArrayList<OIndex<?>>();
      for (final OIndex<?> index : indexManager.getClassIndexes(owner.getName())) {
        final OIndexDefinition definition = index.getDefinition();

        if (OCollections.indexOf(definition.getFields(), globalRef.getName(), new OCaseInsentiveComparator()) > -1) {
          if (definition instanceof OPropertyIndexDefinition) {
            relatedIndexes.add(index);
          } else {
            throw new IllegalArgumentException(
                "This operation applicable only for property indexes. " + index.getName() + " is " + index.getDefinition());
          }
        }
      }

      for (final OIndex<?> index : relatedIndexes)
        getDatabase().getMetadata().getIndexManager().dropIndex(index.getName());

      return this;
    } finally {
      releaseSchemaReadLock();
    }
  }
Remove the index on property

@deprecated Use {@link OIndexManager#dropIndex(String)} instead.