The 17th Amendment transfers the election of Senators from the State legislatures to the people of the State. To uphold the 10th Amendment (and indeed the rest of the constitution), we should start by repealing the 17th Amendment.
The 10th Amendment states:
The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.
The US Senate was never intended to be direct representatives of the people, but rather representatives of the states. The interests of a State will not always directly correspond with the interests of the people of that State. The primary reason each State has the same number of senators regardless of population is so that each State is equally represented, as it clearly does not provide equal representation of the people.
One of the reasons for the revolutionary war was "taxation without representation", which led to the USA creating a "representative form of government" in which all affected parties had representatives. When we ratified the 17th Amendment, we took the representatives away from the States. The 17th amendment weakened the States by limiting their ability to protect those powers reserved to the States (aka "states rights") and shifted the balance of power in favor of the federal government. In doing so, we limited the ability of the States to defend their sovereign powers and to reign in the federal government in the normal course of business.
To correct this imbalance, some people have proposed adding a "repeal amendment" that allows a majority of States to repeal any federal law. Strictly speaking, such an amendment is not necessary. Here is the text of Article 5 of the US Constitution:
The Congress, whenever two thirds of both Houses shall deem it necessary, shall propose Amendments to this Constitution, or, on the Application of the Legislatures of two thirds of the several States, shall call a Convention for proposing Amendments, which, in either Case, shall be valid to all Intents and Purposes, as part of this Constitution, when ratified by the Legislatures of three fourths of the several States, or by Conventions in three fourths thereof, as the one or the other Mode of Ratification may be proposed by the Congress; Provided that no Amendment which may be made prior to the Year One thousand eight hundred and eight shall in any Manner affect the first and fourth Clauses in the Ninth Section of the first Article; and that no State, without its Consent, shall be deprived of its equal Suffrage in the Senate.
This makes 2 things clear:
1. That 3/4 of the states can effectively repeal any Federal law by calling a constitutional convention (2/3 of the states) which proposes and passes (3/4 of the States) an amendment which nullifies that Federal law. It's a rather slow and clumsy way to do it, but it's possible.
2. That Senators are representatives of the States, not of the people.
Senators are supposed to be the representatives of the states, representing the interests of the State governments. Repealing the 17th Amendment would go a long way toward restoring the representatives of the States, and restoring the balance of power.
That doesn't mean adding a "repeal amendment" has no value. Repealing the 17th Amendment is the first step in restoring the balance of power, but it might not be the only step, especially given the size and power the federal government has amassed in the 97 years since the 17th Amendment was ratified. A "repeal" amendment would simplify the process of state nullification of unjust federal laws, and for that reason, it may be useful. Because an action taken under a proposed repeal amendment would occur by action of the State legislatures (direct representatives of the people of each State), or by the people themselves. In effect, it would be one more check on the power of the federal government.