C, 87 bytes

#include<stdio.h>
#define S(n) for(n=0;n<26;n++)
main(){int i,j;S(i){S(j)putchar(65+(j<i?i:j));puts("");}}

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C, 87 bytes

#include<stdio.h>
#define S(n) for(n=0;n<26;n++)
main(){int i,j;S(i){S(j)putchar(65+(j<i?i:j));puts("");}}

Try it online!