If you install Windows NT after Windows 95, by default dual-boot will be set up on your PC.
However, if you then delete the /winnt directory to remove Windows NT, your system will still display a boot menu when started.
To remove that menu, back up your files (just to be safe), then boot from a Windows 95 Startup Disk (see Add/Remove Programs in Control Panel to create one), and execute the following command:
sys c:
After it completes you'll see the message "System Transferred". Remove the diskette and reboot, and your system will boot straight into Windows 95.