In most cases, you need not reconfigure the port number.
If you must, then you can use the Registry Editor to edit its value in the HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE\OracleMTSRecoveryService\Protid_0 Registry Editor key to any available port within the range 1024 to 65535.
During installation, Oracle Universal Installer takes the value for the port from the key, if it exists. Otherwise, a free port ranging from 49152 to 65535 is chosen.