Uninstall

In this section, we will show you how to uninstall Kylin.

The steps to uninstall Kylin and remove all relevant data are as follows:

Run the following command on all Kylin nodes to stop the Kylin instance:
```
$KYLIN_HOME/bin/kylin.sh stop
```
Data backup (optional):
- Backup metadata before full unloading so that it can be restored when needed.
```
$KYLIN_HOME/bin/metastore.sh backup
```
  Notice: We recommend that you copy metadata to more reliable storage devices later.
Please check the configuration file $KYLIN_HOME/conf/kylin.properties to determine the name of the working directory. Suppose your item is:
```
kylin.hdfs.working.dir=/kylin
```
Please run the following command to delete the working directory:
```
hdfs dfs -rm -r /kylin
```
Please check the configuration file $KYLIN_HOME/conf/kylin.properties to confirm the name of the metadata table. Suppose your item is:
```
kylin.metadata.url=kylin_metadata@jdbc
```
Please run following commands to delete metadata tables:
- If you are using PostgreSQL as your metastore:
  - Set environment variable of PostgreSQL user password. Say your PostgreSQL user password is kylin:
    export PGPASSWORD=kylin
  - Delete metadata tables:
    /usr/pgsql-10/bin/psql -h {hostname} -p {port} -U {user} -d {database} -c "drop table if exists {metadataUrl}"
    Below is a description of the fields:
    - hostname: PostgreSQL host address;
    - port: PostgreSQL server port;
    - user: PostgreSQL user password;
    - database: PostgreSQL database name;
    - metadataUrl: PostgreSQL metadata table name, it is kylin_metadata in this example.
  You can also log in to PostgreSQL and query drop table if exists {metadataUrl} to delete your metadata table.
- If you are using MySQL as your metastore, run the following command to delete your metadata tables:
```
mysql -h{hostname} -u {root} -p{password} -D {database} -e "drop table if exists {metadataUrl}"
```
  Below is a description of the fields:
  - hostname: MySQL host address;
  - user: MySQL user name;
  - password: MySQL user password, please note that there is no space between -p and password;
  - database: MySQL metadata database name;
  - metadataUrl: MySQL metadata table name, it is kylin_metadata in this example.
  You can also log in to MySQL and query drop table if exists {metadataUrl} to delete your metadata table.
Run the following commands on all Kylin nodes to delete the Kylin installation directory:
```
rm -rf $KYLIN_HOME
```

At this point, the Kylin uninstall is complete.