public void unsetSchemaTemplate() {
    this.schemaTemplateId = -1;
  }
In InternalMNode, schemaTemplateId represents the template set on this node. The pre unset
mechanism is implemented by making this value negative. Since value 0 and -1 are all occupied,
the available negative value range is [Int.MIN_VALUE, -2]. The value of a pre unset case equals
the negative normal value minus 2. For example, if the id of set template is 0, then - 0 - 2 =
-2 represents the pre unset operation of this template on this node.
iotdb-core/confignode/src/main/java/org/apache/iotdb/confignode/persistence/schema/mnode/info/ConfigMNodeInfo.java