Can I remove my old electrical panel and junction the lines to new panel?

Most cities will require you to pull a permit and hire a licensed electrician so ask the city first. What do you mean by "and junction the lines "

It can be done. I would put in a switch box to make the connection to the new box. I would check your local codes to make sure it is legal. A switch would serve as a junction box as well as a good way to shut down power if you need to work on your service. Obviously you need to have power off before you start removing your service panel. Hope this helps.