You could use the RIGHT() part of the string filtering wher the firts is a number eg:
SELECT right(my_column, LENGTH(my_column)-1)
FROM my_table
WHERE my_column REGEXP '^[0-9]'
for update (remove the number ) you could use
Update my_table
set my_column= right(my_column, LENGTH(my_column)-1)
WHERE my_column REGEXP '^[0-9]'
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solved How to remove first letter if it is number in sql?