Deleting the nth row mysql

You need a little trick like this

delete from prototype_1 where id = (select id from (select id from prototype_1 order by id limit 1,1) as t)

From docs

The LIMIT clause can be used to constrain the number of rows returned by the SELECT statement. LIMIT takes one or two numeric arguments, which must both be nonnegative integer constants

(...)

With two arguments, the first argument specifies the offset of the first row to return, and the second specifies the maximum number of rows to return. The offset of the initial row is 0 (not 1):