Remove adjacent duplicates in linked list in C

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C

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As the title mentioned, I have to remove adjacent duplicates in linked list such that if input is 'google', output should be 'le'. I'm supposed to code it in C. I've written 70% of the code, except that I don't know how to continuously loop till all adjacent duplicates are removed. I'm removing adjacent duplicates in remove_adjacent_duplicates() function, and since I don't know how to put terminating condition in loop, I've merely used if-else loop. But my code in remove_adjacent_duplicates() function might contain mistakes, so please rectify it if any and please give solution to looping till all adjacent duplicates are removed. Here's my code-

What I have tried:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

struct node //node creation
{
  char data;
  struct node *next;
};

void remove_adjacent_duplicates(struct node** head_ref)
{
    struct node* current = *head_ref; 
    struct node* cnext = NULL; //the one next to current one
    int flag=0;
    
    cnext = current->next; //storing next
    //printf("%c %c %d\n",current->data,cnext->data,flag);
    
    if(cnext->data==current->data)
        {
            flag=1;
            while(cnext->data==current->data)
            {
                cnext=cnext->next;
            }
            current=cnext;
            cnext = current->next; //storing next

        }
        
    else
        {
            current=current->next;
            cnext = current->next; //storing next
            
        }
    //printf("%c %c %d\n",current->data,cnext->data,flag);
    if(flag) *head_ref = current;
    
}

void push(struct node** head_ref, char new_data)
{
    struct node* new_node = (struct node*)malloc(sizeof(struct node));
    new_node->data = new_data;
    new_node->next = *head_ref;
    *head_ref = new_node;
}


void printList(struct node* head)
{
    if (head == NULL)
    {
        printf("NULL\n\n");
        return;
    }
    
    printf("%c->",head->data);
    printList(head->next);
}

int main()
{
    char s[100];
    int i;
    struct node* a = NULL;
    
    printf("Enter string: ");
    scanf("%s",s);
    
    for(i=strlen(s)-1;i>-1;i--){
        push(&a, s[i]); //last in first out, so in reverse g is last but first to come out
    }

    printf("\nConverting string to linked list: \n");
    printList(a);

    
    //printf("%c",current->data); prints first letter of a 
    remove_adjacent_duplicates(&a);
    
    printList(a);


    return 0;
}