How to secure the access switch?

we can secure access to switch by implement the port security violation system.

It is depen on what kind of security you are looking for.

1) You can have console login authentication to prevent console access from unauthorized access.

2) implement Port Security.

3) Radius server authentication.

and etc..

Kindly read white papers and manuals from the vender related to the product.

set port security for user

set vlan

set vtp