Sure, I can help you with that!

To subtract 3 hours from the current time in Excel, you can use the NOW() function to get the current date and time, and then subtract 3 hours from it using the TIME() function.

Here are the steps:

1. In a cell, type =NOW() to get the current date and time.
   
2. To subtract 3 hours from the current time, you can use the following formula: =NOW() - TIME(3,0,0)
   
   The TIME() function takes three arguments: hours, minutes, and seconds. In this case, we want to subtract 3 hours, so we use 3 for the hours argument, and 0 for the minutes and seconds arguments.
   
3. Press Enter to get the result.
   
   The cell should now display the current date and time minus 3 hours.
   

That's it! I hope this helps.