When untied inputs are necessary, what is the technology to use for an OR gate?
You can tie the input to ground, directly or through a jumper (jumper is useful if you want to change something later). Tying an input of an 'OR' gate to logic '1' would not make much sense since the output would always be high, but if you want to do that, it's good practice to use a series resistor of about 1K with LSTTL (practice from TTL days). 

If you are using LSTTL or TTL, leaving an input open will result in a logic '1' but it can also pick up noise. 

If you use HC or other CMOS logic families you should always tie all unused inputs either high or low, on all gates (even unused ones- this is good practice with TTL/LSTTL but essential with CMOS).