I see. Replaced goto with continue and getch() with getchar().
Code:
do
{
printf("\nChoose a number: \n");
scanf("%d",&choice);
if(choice != 1 && choice != 2 && choice != 3 && choice != 4 && choice != 5)
{
printf("The number you entered doesn't exist. Try again.\n");
continue; // instead of goto
}
for(i=0;i<len;i++)
{
if(nums[i]==choice)
{
for(j=i;j<len;j++)
nums[j]=nums[j+1];
len--;
}
}
printf("\nNumbers left:");
for(i=0;i<len;i++)
{
printf(" %d",nums[i]);
}
}
while(len!=0);
printf(" none\n");
getchar(); // instead of getch();