I've tried removing
data-validation Tag from password input but it didn't work for Reset Password, New Password, and Change Password.
I've created a file
And modified following function and return true.
You can disable password validation from the admin panel for that
Stores -> Configuration -> Customers -> Customer Configuration in
Password Options section there is a field
Number of Required Character Classes set
1 in that field and in
Minimum Password Length set
1 and save the configuration.
Now it will accept any 1 character in password.