You have to look at the TE form and MASU form of 帰る.
For a RU verb, you would just knock off the RU and add TE. ie. 食べる becomes 食べて.
But for U verbs, you have to change it a bit. For 帰る in particular, it becomes 帰って. This is NOT the same for all U verbs.
Because the る in 帰る becomes a り instead of disappearing when it becomes a MASU form, it is considered a RU verb.
More information about formatting options
You have to look at the TE
You have to look at the TE form and MASU form of 帰る.
For a RU verb, you would just knock off the RU and add TE.
ie. 食べる becomes 食べて.
But for U verbs, you have to change it a bit.
For 帰る in particular, it becomes 帰って.
This is NOT the same for all U verbs.
Because the る in 帰る becomes a り instead of disappearing when it becomes a MASU form, it is considered a RU verb.