How to delete defulault default boot images in beagleboneblack?

i bought a new beagle bone black through amazon.in today, whenever powerup the board, its automatically boot from emmc, not from sdcard, how to delete the emmc bootfiles?
Beaglebone black vendor is embest

Sdcard boot is not working.
Please help me to sortoiy this problem?

On Fri, 8 Mar 2019 12:10:53 -0800 (PST),
chandrumuthu011@gmail.com declaimed the
following:

i bought a new beagle bone black through amazon.in today, whenever powerup the board, its automatically boot from emmc, not from sdcard, how to delete the emmc bootfiles?
Beaglebone black vendor is embest

Sdcard boot is not working.
Please help me to sortoiy this problem?

  Well... Have you held down the boot button while applying power. That
is what the older systems required -- which leads to...

  What version of the OS is installed on the eMMC? Even the last flasher
images of Wheezy (Debian 7) rewrote the u-Boot with one that would
automatically boot from the SD card if it is found.