Is it permissible to take sweets placed for guests in company offices without informing their owners, and what are the limits of that?

If you know or strongly believe that the office owners have given permission to eat the sweets, then there is no harm in doing so, based on the Almighty's saying: "There is no blame upon the blind..." [Qur'an 24:61] and what has been narrated from scholars regarding the permissibility of eating from the homes of those mentioned if their consent is known or strongly believed.

However, if their consent is not known or not strongly believed, then it is not permissible to take anyone's property except with their willing consent; due to the Prophet's (peace be upon him) saying: "It is not lawful for a person to take his brother's property without a just right," and "It is not lawful for a man to take his brother's stick without his willing consent."