add domain for the github pages, but not effect the project page

Question

for example:

if I set the CNAME: exampledoamin.github.io -> blog.mydomain.com

my projectpage will point to exampledoamin.github.io/myprojectpage -> blog.mydomain.com/myprojectpage

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now I want to my projectpage use the default domain which the github given,

exampledoamin.github.io/myprojectpage.