If a project has multiple branches and you only want to keep one branch, you can consider deleting a branch remotely with the git command.
For example, there are now two branches, one is master and the other is lunbo. As shown in Figure 1 below:
figure 1
Now want to delete the master branch; do the following:
git branch -r (view the list of remote branches) as shown in Figure 2:
git branch -r -d origin/master (delete the local remote branch) as shown in Figure 3
git push -u origin master ( delete the branch on the git server remotely ) as shown in the figure 4
The problem in Figure 4 is because the master is the default branch, as long as you change the default on github, as shown in Figure 5 (this is after modification):
figure 2
image 3
Figure 4
Figure 5