See the explanation below.
Explanation
SQL Data Warehouse compute resources can be scaled by increasing or decreasing data warehouse units.
1. Click SQL data warehouses in the left page of the Azure portal.
2. Select datawarehouse from the SQL data warehouses page. The data warehouse opens.
3. Click Scale.

4. In the Scale panel, move the slider left or right to change the DWU setting. Double the DWU setting.

6. Click Save. A confirmation message appears. Click yes to confirm or no to cancel.

Reference:
https://docs.microsoft.com/en-us/azure/sql-data-warehouse/quickstart-scale-compute-portal