Step 1:

Open up cmd.exe (note: you may need to run it as an administrator, but this isn't always necessary), then run the below command:

netstat -ano | findstr :<PORT>

(Replace <PORT> with the port number you want, but keep the colon)

The area circled in red shows the PID (process identifier). Locate the PID of the process that's using the port you want.

Step 2:

Next, run the following command:

taskkill /PID <PID> /F

(No colon this time)

Lastly, you can check whether the operation succeeded or not by re-running the command in "Step 1". If it was successful you shouldn't see any more search results for that port number.

Is there any thing like a pipe or similar that I can use on Windows OS to run this command in one line?

Both cmd.exe and PowerShell support pipes from one command to another. In PowerShell something like (this should be on a single line on the command line, or use ` to escapte newlines in a script):

netstat -ano
 | select -skip 4 
 | % {_ -split ' {3,}'; New-Object 'PSObject' -Property @{Original=$_;Fields=$a}} 
 | ? {$_.Fields[1] -match '15120$'}
 | % {taskkill /F /PID $_.Fields[4] }

Where:

• Select -skip 4 skips the first four header lines. (Select is short for Select-Object used to perform SQL SELECT like projects of objects.
• % is short for Foreach-Object which performs a script block on each object ($_) in the pipeline and outputs the results of the script block to the pipeline. Here it is first breaking up the input into an array of fields and then creating a fresh object with two properties Original the string from netstat and Fields the array just created.
• ? is short for Where-Object which filters based on the result of a script block. Here matching a regex at the end of the second field (all PowerShell containers a zero based).

(All tested except the last element: I don't want to start killing processes :-)).

In practice I would simplify this, eg. returning just 0 or the PID from the first foreach (which would be designed to ignore the headers) and filter on value not zero before calling taskkill. This would be quicker to type but harder to follow without knowing PowerShell.