No just ignore pronounce ㅅ in there. It is pronouced "eop"
If you add to "s", it will sound really funny ㅋㅋㅋㅋ
when you say "없다" , just ignore it and pronounce "eop-dda"
But remember this, when you face "ㅇ" the next of "없" you should pronouce ㅅ too:
"없어" -> 없 어 -> 업 써 = eop - SSer
Basically, a consonant word "ㅇ" is dealed with No phonetic value; So "ㅅ" , as a main phonetic value "S", replace the position of "ㅇ".