In 2015, Trump promised to terminate DACA on his first day as president.
To accomplish that, Trump could have written a binding Executive Order on his first day as president that said...
“The DACA kids and their parents are unlawfully present in the USA. I order the Secretary of Homeland Security to remove all of them.”
The language in that theoretical Executive Order comes directly from the relevant federal statute - The Immigration and Nationality Act of 1965.
Since Trump's order would have been a lawful administration of a lawful statute, it could not be challenged in court.
Instead, breaking his campaign promise, Trump ignored DACA for seven months.
Then, in September 2017, ten Republican state Attorneys General threatened to sue Trump over DACA, forcing Trump to act.
Trump chose not to write a binding Executive Order that would terminate DACA.
Instead, Trump instructed Attorney General Jeff Sessions to write to the Secretary of Homeland Security and tell her that DACA was an unconstitutional order and should not be enforced.
The Trump-Sessions memo to the DHS Secretary was disingenuous.
Both Trump and Sessions clearly understand that no federal court in the country would allow Jeff Sessions to decide what is - or is not - constitutional.
A federal judge in San Francisco rejected the Sessions memo, and DACA is currently being enforced almost exactly as it was when Trump took office.
Bottom Line...
Trump will never deport any illegal immigrants unless they have been convicted of a felony.
I suspect bad advisers and conflicting advice. Hence the turnover.