Can't upload code on my arduino

When i am trying to upload my code to my Arduino Uno board it is giving me the following error:

./opt/arduino-builder/arduino-builder -compile -core-api-version 10611 -hardware opt/arduino-builder/hardware -hardware ./opt/cores -tools opt/arduino-builder/tools -tools ./opt/tools -built-in-libraries opt/libraries/latest -logger humantags -fqbn arduino:avr:uno -build-cache /tmp -build-path /tmp/848176081/build -verbose -prefs -prefs -prefs -libraries /tmp/848176081/custom -libraries /tmp/848176081/pinned /tmp/848176081/obstacle_avoiding

Sketch uses 2456 bytes (7%) of program storage space. Maximum is 32256 bytes.

Global variables use 218 bytes (10%) of dynamic memory, leaving 1830 bytes for local variables. Maximum is 2048 bytes.

Programming with: Serial

Flashing with command:/home/flamingdragons/.arduino-create/arduino/avrdude/6.3.0-arduino9/bin/avrdude -C/home/flamingdragons/.arduino-create/arduino/avrdude/6.3.0-arduino9/etc/avrdude.conf -v -patmega328p -carduino -P/dev/ttyACM0 -b115200 -D -Uflash:w:/tmp/arduino-create-agent231606963/obstacle_avoiding.hex:i

avrdude: Version 6.3, compiled on Jan 17 2017 at 11:00:16

Copyright (c) 2000-2005 Brian Dean,

Copyright (c) 2007-2014 Joerg Wunsch

System wide configuration file is “/home/flamingdragons/.arduino-create/arduino/avrdude/6.3.0-arduino9/etc/avrdude.conf”

User configuration file is “/home/flamingdragons/.avrduderc”

User configuration file does not exist or is not a regular file, skipping

Using Port : /dev/ttyACM0

Using Programmer : arduino

Overriding Baud Rate : 115200

avrdude: ser_open(): can’t open device “/dev/ttyACM0”: Permission denied

avrdude done. Thank you.

have you tried changing the com port?

Are you using the ONLINE EDITOR ?
Not familiar with the MAC but it looks more like the DESKTOP version you are using ?