SuperTech,

You have a few options open to you, and not knowing your exact situation I'm unsure which one will suit you best.

You can reduce the size of your .ost file using the following guide, scroll down to find the .ost section:

https://support.office.com/en-ie/art...d-5e094e4b032b

You can delete your .ost file if you wish, however Outlook will simply re-create it next time it is opened, and I'm fairly sure the size will not be reduced by this process.

It would help to know your situation, are you hoping to move your .ost file to another drive? This can be done by following the instructions in the below article. You can either create a new .ost in the new location, then delete the old one. Or you can move your current .ost to the new location.

https://support.office.com/en-us/art...6-3a788c79b7f0

I hope this helps.