How to change to another template and remove login from modx?

How to change to another template?
How to remove login block from modx?

1) Each document has a template assigned, you can change it on its main page,
it is a drop-down menu...

2) The login block for the manager?
It is on assets/templates/YOURTEMPLATE/ directory...
but why do you want to remove it?
how are you going to access the manager?

if your talking about a login block in the front...
there must be a chunk or a snippet in the content or sidebar
that you can delete by editing the page or chunk or snippet...