@lp101 they wont be able to use link aggregation, as you need dual links (or more) between the same two switches (or switch stacks).
@Dasilva13 it would be better if you could change your switch design. It would be better to have a pair of core switches, and then run a pair of links between that and each floor, rather than chaining them together floor to floor.
If you need to keep the current design then make each port connecting to another switch a trunk port. Leave RSTP turned on, and it will knock one link out to get rid of the loop. You should make one switch the "core" or "main switch", and lower its spanning tree priority (Switch/Switch Settings/under "STP bridge priority" choose the switch/lower the priority to something like 16384).
I would not both using root guard. I would make sure every port that is not connected to something that does not need VLAN trunking (aka ports to workstations) are made access ports.