How to reduce sapdata_1 file size in SAP

Hi All,

We have installed sap on sybase 15.0.121 on windows ,at the time of installation by mistake we given sapdata_1 file Initial size 300GB

Now i want to reduce the sapdata_1 file to 120GB as drive is showing full.

Please explain how can i reduce

Please explain step by step.

Regards

Chandra