1. Go to settings.cpp and add the following code to the misc section:
char misc_NameChange = 0;

Picture: http://prntscr.com/iscl8o

2. Go to settings.h and add the following code to the misc section:
extern char misc_NameChange;

Picture: http://prntscr.com/iscla9

3. Go to your client.cpp inside of the misc tab where you want your name changer to be, and paste this:

static char buf2[128] = { 0 };
ImGui::InputText("##CustomName", buf2, 16, Settings::Misc::misc_NameChange);
if (ImGui::Button("Apply Custom Name")) {
ConVar* Name = Interfaces::GetConVar()->FindVar("name");
*(int*)((DWORD)&Name->fnChangeCallback + 0xC) = 0;
Name->SetValue(buf2);
}

Picture: http://prntscr.com/isclc4

4. You're finished! It was that easy!
Final product: http://prntscr.com/iscui5

All credit goes to Chez1863
https://pasters.cc/member.php?action=profile&uid=55
Please +rep him!!