Using steps mentioned below, you can grant admin access to anyone on your Blogger.com (BlogSpot) blog without sharing your Gmail/Blogger.com account password with them.
1. Log into Blogger.com Dashboard.
2. Click on “Settings” link for the blog. (see below)
3. Next click on “Permission” tabs and then “Add Author” button. (See below)
4. Just type email address of users whom you want to invite on your blog and click “Invite” button. (See below)
5. This will email an invitation link. Once the other person accepts your invitation, go back to the same “Permissions” page above.
Now you will see a “Grant admin privileges” link next to email address as shown below. Just click on it and your are done! 
