I don't understand the question.
What do you mean by separate administrator template.

If you want specific joomla templates installed, see the tutorial video cp-05.
www.jms2win.com/tutorial#jms12x-CP-05

in the process of slave creation we can specify the templates path for site templates, but do not have option for administrator templates.

If i want to have separate template folder like administrator/templates what to do.

suppose if i created slave, it will create slave folder, inside slave folder templates,images, tmp etc will be created and administrator, components and modules etc will be link to master. i just want separate administrator template like how we are having for site templates.

i do not want to copy full administrator instead symbolic link.

For the /administrator/templates, this is not possible because to do that this suppose that the /administrator is NOT a link but a reall directory like I did it for the front-end.

The only solution is to create many /administratrator/templates/xxxx directories.
Where xxx is the template. In general, you can duplicate such templates sub-directories to allows you change its content

but if i have 5 slave sites and created sub-directories(templates), all the templates will show to every slave.

if suppose i created template_slave1, template_slave2 etc.

is it possible to restrict admin from slave1 can use or ( see) only template_slave1.

NO this is not possible.
The back-end has the /administrator directory that is a symbolic link and the objective it not to replicate all the Joomla PHP code for each website.
Create what you request mean that all the directory structure of the administration directory should be replicated in each website and each time you install an extension and so on for all the website.

This is not available and the objective also is not to modify joomla itself to change the way they manage the templates.

Sorry but I have no solution for that.

Install suPHP, there is no other way to solve the permission issue (nobody vs user).