How can we delete some element/data from a structure ?

How can we delete some element/data from a structure ?

Hello there
We all know that we can use Structure in C programming and also can store structure data in HDD by using fwrite() function. However, I am making a simple mini project with C programming. With this project user will be able to store employee details in HDD and also will be able to manage them. However, in that project I will need to store structure data in a .dat file and will need to give option to remove any data from that file. I mean user will be able to delete any data from the structure as well as from the .dat file. I have tried much but couldn't do this. Actually I am little confuse about this. I don't know how can I delete data from that file. Do you guys have any idea about this ? Any algoritms to delete data from structure as well as from file ??