awk 'BEGIN{FS="";OFS="https://stackoverflow.com/"}{NF-=3;print}' file
1/2/2/0/3
6/4/5/8
6/4/5/8
1/0/3/3/6
1/0/3/6/6
1/0/3/6/6
1/0/3/6/6
8/1
2
solved Insert delimiter between digits in linux
awk 'BEGIN{FS="";OFS="https://stackoverflow.com/"}{NF-=3;print}' file
1/2/2/0/3
6/4/5/8
6/4/5/8
1/0/3/3/6
1/0/3/6/6
1/0/3/6/6
1/0/3/6/6
8/1
2
solved Insert delimiter between digits in linux