1. 事实上，out of the reach of sb和out of reach of sb两者均可用，且以不用冠词为常见。如：

She didn’t understand why the TV was kept out of reach of the patients.

The ornaments had been put out of reach of the children’s prying fingers.

比如下面一句摘自Merriam-Webster's Advanced Learner's Dictionary：

Keep all medicines out of (the) reach of children. [=keep medicines in a place where children cannot reach them.]

句中的 the 被加了括号，说明可以这个定冠词可以省略。

2. 顺便说一句，短语with (easy) reach of…也通常不用定冠词the。如：

We live within (easy) reach of the station.

Verona and Padua are both within easy reach for day trips.

The house is within easy reach of schools and sports facilities.

3. 但是beyond the reach of…则通常要用定冠词the。如：

Martin was living in Brazil, beyond the reach of the FBI.

The shot was well beyond the reach of the goalkeeper.

Achievements like these are beyond the reach of ordinary players.

Elizabeth now felt herself to be beyond the reach of the Catholic Church.