How do I disable NetBios TCP/IP?

BIOS is something used in PCs. Macs tend to use a different method.

What are you trying to accomplish?

In general Macs do not open network ports or have services running unless either they are absolutely necessary e.g. DNS lookups, or you turn the relevant service on. So the first thing to do is check your File Sharing settings. Based on your description it sounds like File Sharing is enabled (ticked).

1. Go to System Preferences
2. Click on Sharing
3. Click on File Sharing (on the left)
4. If needed unlock the padlock in the bottom left
5. Then click the options button on the right

If 'Share files and folders using SMB' is ticked this will cause NetBIOS to run and use those network ports and also likely port 445

If 'Share files and folders using AFP' is tucked this will cause Apple File Sharing to run and use network port 548

It sounds like you want to un-tick the SMB option.

You may also want to make sure the built-in Firewall is turned on since you seem to be concerned about network security.

1. Go to System Preferences
2. Click on Security & Privacy
3. Click on Firewall at the top
4. If needed unlock the padlock in the bottom left
5. Turn the Firewall on (if it is off)

SMB is a name for the protocol Microsoft use for file sharing just like AFP is the name use for the protocol.

SMB includes using NetBIOS as both are part of the suite of protocols used for Windows File Sharing. Therefore if you turn off SMB you turn off NetBIOS.

Microsoft like making things un-necessarily complicated. Not only do we have SMB and NetBIOS but there is also CIFS. Contrast this to Apple which has just AFP and nothing but AFP. 😕 Microsoft also like constantly renaming the same thing in the false hope this will magically make the product more attractive. Messenger had more names than version numbers!

So try turning SMB off.