What is the correct form?
( ) It would be easier to cut the cloth with a bigger scissors.
( ) It would be easier to cut the cloth with bigger scissors.
'It would be easier to cut the cloth with bigger scissors.'
is the correct form.
'Scissors' is a plural noun, so you can never say 'a scissors'. If you want to use a singular article you can say 'a pair of scissors'. It's the same as glasses, pants, jeans ... these are plural nouns, so you can't put 'a' directly before them.