When there is no requirement or obligation to perform a specific task, there are many synonyms that can be used instead of "be no need to do sth". Some of the alternatives include "be unnecessary", "be superfluous", "be redundant", "be dispensable", "be optional", "be unessential", "be inconsequential", "be insignificant", "be irrelevant", and "be immaterial". These words convey a sense of flexibility and choice, suggesting that the action is optional and not critical. It is important to choose the appropriate synonym based on the context and tone of the sentence to convey the meaning accurately.